This summer, I received a call from Jonathan Rubin of Guerrilla Calculator Accessories, a company that makes cases, screen protectors, and other products for TI graphing calculators. He asked if I had seen TechPoweredMath's review of Guerrilla's accessories, and offered to send a selection my way so that I could share my experiences with Cemetech. We eventually coordinated the exchange, and after about a month of using Guerrilla's products, I believe I can fairly share my thoughts on their products with all of you.

First of all, why would you want calculator accessories in the first place? Judging by the popularity and my Ultimate Calculator projects and the fact that few people have attempted similar hacks, everyone wants to customize their gadgets, but few are willing to risk permanently changing or damaging their devices along the way. Guerrilla aims to capitalize on this demand for individuality by offering colorful faceplates and slide cases for the TI-84 Plus and TI-89 Titanium series of graphing calculators, as well as help protect your TI-84 Plus, TI-89 Titanium, and TI-Nspire CX calculators with soft silicon cases and screen protectors. Read on for my full thought on the value, quality, and cost of Guerrilla's range of offerings. In addition, keep your eyes open for Cemetech's Thanksgiving Lightning programming contest, which will give you the chance to win some of these Guerrilla accessories as prizes!

Guerrilla sent me ten samples to review: Two TI-84 Plus/TI-89 Ti slidecases, one TI-Nspire CX slidecase, one TI-84 Plus silicone soft protective case, one TI-Nspire CX soft protective case, one orange TI-84 faceplate, and three sets of screen protectors, for the TI-84 Plus, the TI-84 Plus C Silver Edition, and the TI-Nspire CX. I tried out each of the items on calculators in my extensive collection. In the case of the TI-84 Plus C Silver Edition and TI-84 Plus Silver Edition accessories, I got to see how the items held up to my daily calculator use. I'll start with the one item I had concerns about, the slidecases, then continue with the faceplate, silicone cases, screen protectors.

My first impression of the slidecases and faceplate was that they were identical in shape, material, and weight to the original TI cases and faceplates, but much more colorful. Guerrilla sent me three designs: one space scene, one with abstract red and pink hearts, and one with abstract paint splatters. I ended up testing out the space case on my TI-84 Plus C Silver Edition, although I tried all the cases on each model they fitted. I found the quality to be good: the cases snapped nicely onto the calculators, the decals seemed well-protected against scratches and gouges, and the colors remained vibrant. Unfortunately, when pulled off the front and placed on the back of the TI-84 Plus-family calculators and the TI-89 Titanium, it is very hard to get the slidecases off again. I haven't determined why this is true of the Guerrilla cases and not TI's own cases, but it was my only negative experience with the products. The friction between the wide rubber pad on the bottom of the back of the calculators and the Guerrilla cases seemed much higher than the friction between that pad and TI's cases, and it probably bears examining whether small case shape differences or just the material of the case is to blame. If you don't put your slidecase on the back of your calculator when you're using it, you won't run into this issue. Important note: the Guerrilla website labels several TI-83 Plus cases (which fit the TI-83, TI-83 Plus, and TI-86, and TI-89 non-Titanium calculators) as TI-84 Plus cases, so if you do explore their products, make sure you check the pictures of the slidecases against your calculator's original case.

The orange TI-84 Plus faceplate seemed of high quality as well; it fit just as well as TI's own faceplates and appeared to have equally scratch-resistant key labels. If you're looking for more faceplate colors, you can certainly take a look at Guerrilla's offerings, though TI also offers solid-color faceplates.

Of the various items, the silicone cases are the item for which I personally have the least use. Although I dropped my trusty old TI-83 calculator many a time when I used to program it walking to and from high school, it survived, and I treat my more delicate TI-84 Plus C Silver Edition with much more care. I do note that an unfortunate bounce of the brand-new TI-84 Plus Silver Edition I bought in 2005 with my hard-earned cash shattered the screen about a day after I bought it, and had it been nestled in a silicone bumper case, it very well may have survived the fall. The silicone cases are about the same thickness as the keys, so the keys appear flush with the case. I tend to touch-type on my calculators, so I found that unusual, but trying to use the cases for a few hours, I found that I got used to it. Whereas the slide cases from Guerrilla are covered in colorful designs, the silicone cases are in single bold colors, which Lucas from TechPoweredMath argues seem more masculine. I certainly see that point, but I also found the slide cases (including the heart-covered one) to provide plenty of unisex pizazz.

Finally, the screen protectors are valuable for the TI-84 Plus C Silver Edition and the TI-Nspire CX and CX CAS. The screen protector packages are surprisingly complete, including microfiber clothes to clean your screen before you apply the protectors, the protectors themselves, and a rubber squeegee to push out any air bubbles. Since my TI-84+CSE and TI-Nspire CX (and CX CAS) have already accumulated quite a few scratches, I was happy to be able to protect them from further damage, and once I applied the protectors and turned on my calculators, I couldn't tell they were there. On the TI-84 Plus and TI-84 Plus Silver Edition (ie, monochrome) calculators, I was less convinced of the value of the screen protectors. I see very few scratches monochrome screens among the second-hand repaired calculators in my collection, while pressure damage, which a screen protector will not prevent, is a real threat to the monochrome calculators. The long and short of it: if you have a color-screen calculator, a screen protector is an excellent idea. If you have a monochrome calculator, I'm more ambivalent.

If you're here at Cemetech, there's a good chance you're enthusiastic about using or even programming your calculator, which means you put your calculator's durability through its paces. You probably also want to make your calculator as spiffy and unique as possible. Guerrilla's slide cases, faceplates, silicone cases, and screen protectors are all great options, as long as you're also aware that Texas Instruments also offers slide cases and faceplates. I found the products to generally be of a uniform good to high quality. My gripes were with the slide cases and faceplates: difficulty pulling slide cases off the back of calculators and emblazoned logos on the slide cases and logos. You can find more information about Guerrilla's products on their website. Finally, if you covet the products in this review but don't have the money for them, you should enter our impending lightning contest.
Very thorough review(s). I can see our members wanting and buying these! Including myself Wink
Thank you for this review! Incidentally, I just noticed Guerrilla products on eBay today, and was curious about them. I like the fancy slide covers. My message to Guerrilla would be, I hope they make the cases themselves in custom colors - thats something I'd like even more!
comicIDIOT wrote:
Very thorough review(s). I can see our members wanting and buying these! Including myself Wink
Thanks! I waited quite some time in between getting the samples and posting this, but hopefully the delay is understandable in terms of getting a real-world feel for using them.

CalebHansberry wrote:
Thank you for this review! Incidentally, I just noticed Guerrilla products on eBay today, and was curious about them. I like the fancy slide covers. My message to Guerrilla would be, I hope they make the cases themselves in custom colors - thats something I'd like even more!
Like, the case of the calculator? I sadly bet that would not be a very popular item, in terms of how many people would be willing to buy them and dissect their calculators. I know many among us would certainly be interested, though.
Any custom PRIZM cases?
flyingfisch wrote:
Any custom PRIZM cases?
Sadly, no. However, I've been meaning to test if any of the screen protectors work on the Prizm, given how terribly scratched those screens get. I will let you guys know once I check.
*bump* Since I can't find a more appropriate recent topic, I have added this to my random wishlist of things I want to buy for myself. Surprisingly cheap, in my opinion, at $17 for six cases: translucent TI-83+ colored slide cases (via

*bumpity bump* My contacts at Guerrilla let me know that they're going to make screen protectors for the Casio Prizm, the Classpad fx-CP400, and the HP Prime. That should be especially good for the Prizm, considering how easy it is to scratch the plastic over the screen. No word yet on availability or pricing.
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