DeadEyeVR Valve Index Wrist Mounted Battery Kit - Charges Your Controllers While Playing

These straps are either loose, or too tight. The battery falls out of them EXTREMELY EASILY, they leave horrible horrible marks on your forearms/wrists and they hurt like hell. I genuinely feel like a lady after taking her bra off when I take these off after using them to assist charging my controllers.

I use these every time I get in VR, which is a lot. Highly recommend. I use these with some 5,200mAh Anker power banks.

I'm a streamer and having this is a great idea, able to extend my game play on VR for extra hour or 2 is amazing, At first I was worried these would be too small but when I got them and put them on they are amazing.

*Let me preface this review by stating that I played with these on for about 10hrs and only played Zenith - The Last City which isn't a crazy movement game compared to something like Beat Saber.*Quality/Design:Quality overall isn't bad. For $20, the quality of the material itself isn't premium by any means but also doesn't feel utterly cheap either. Some minor areas could have used better/cleaner stitching, but as long as you don't abusively stretch or misuse these, they should hold up just fine. The designers didn't take into account the underpart of the wrist straps (specifically the battery part). Depending on your battery, it may bulge into your arm more or less. I wish that they had made it a bit more flush with the arm, even if that means the battery sticks out vertically more.They are not labeled which is left or right, so it was a bit hard to tell how they go on without using the pictures up above on the product page. However, from what I could tell, it doesn't really matter since the design is ambidextrous (or I guess symmetrical would be better word). Smaller strap on top (around the wrist) and longer strap on bottom (around the forearm) or both on the forearm if you have smaller arms like me.The USB cables that come with these wrist straps are actually really quite nice. Braided and fairly durable feeling. My only wish is that both ends were angled to prevent any potential chance of accidentally bending/breaking the USB-C ports on the Index controllers. So, in my opinion, I'd recommend trying to find some dual angled cables (if they exist) to reduce potential strain/breakage on the USB-C side during heated gameplay. Accidents happen!It's a product that could have been a solid 5 star with just a few minor tweaks to the design, even if that meant the cost of the product itself increasing (which would have been worth it in my opinion). They say you get what you paid for, and while I wouldn't say it's fully a bad thing here, there's definitely some personal issues I had with it. More on that further down.Battery Fitment:[https://www.amazon.com/gp/product/B01CU1EC6Y/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1]I'm using these with two Anker's PowerCore 5000 Portable Charger (one for each wrist strap).It, honestly, barely fits. It's ridiculously snug/tight which is good I suppose but any bigger, and it'd probably start stretching too much and ripping the stitching out. 5000 capacity is probably overkill for most, but I'd rather have too much then not enough. These straps apparently also fit Anker's PowerCore+ Mini, 3350mAh lipstick batteries according to one of the questions answered up above.I also personally slide my battery up a bit (as I pictured) so it doesn't interfere with the bottom strap (the much longer of one of the two). Because it's a pretty thick strap you can't really get it under the battery pack like they have pictured (at least with the ones I'm using, these are absolute chonker lipstick batteries..). Imo, it just gets in the way of accessing that strap. I also flipped my batteries around so that the cable comes off the top instead of the bottom. The reason I did this is because having the battery the other way gave the cable less slack to work with. I found that the cable would become very taut with certain wrist movements and I didn't want to risk putting unnecessary stress on the USB Type C ports on my controllers. It's long enough to wrap around the wrist either way, but I found wrapping the cord around my wrist (away from me) was best. No accidental tugging or snagging the cable on the strap itself and heck I didn't even feel the cable at all and often forgot it was there.Personal Fitment:I chose to try wearing them rotated around my forearm instead of how the product page has it to see if it'd work and it did! A lot of people in the reviews pointed out issues with wrist movements wearing it as advertised. So the goal was to give myself as much freedom of wrist movement as possible to try and avoid their issues as much as I could. I found that this setup didn't impede my wrist movements at all during my gameplay. Again, as someone with smaller forearms, it did take a bit of trial and error with the straps to find the right tightness as well as sliding it up my arm (towards my elbow) so that it wouldn't slip or slide. Only had that issue once and it was resolved (for the most part) once I got it right. And while Zenith isn't the craziest arm flailing game, it does have a few mechanics that make you move your arms and I could feel slight sliding as the hours went on (I usually just would tug it back into place every couple of hours or so). While I don't play Beat Saber, I can say with like 70~80% certainty that these wrist straps would probably not stay in place for very long in a game like that. These would be better for less intensive games like VRChat or if you're a dev testing out your VR programs. However, with that said, I will say these are not terribly comfortable to wear for extended periods of time. I managed it because I eventually ignored it and was more focused on my game. I had to tighten them to the right point where they wouldn't slide but also didn't cut off circulation (do use caution!) and it definitely left marks. Also some of the exposed Velcro at times was digging into my arm as well as the rougher, non-padded parts of the Velcro straps. You could probably easily remedy this by wearing a long sleeve or just putting some sort of fabric around your arm first and then the strap over that to cushion.Final Thoughts:Would I personally recommend these to people? It's hard to say, for the price they are fantastic however you really have to ask yourself if you actually need these.For me, by the time eye strain and sometimes headaches kick in, my controllers are usually about to die anyways so it's a good time to just stop playing and take a break. So in my use case it's a slight a waste of money but hey, I don't have a spare set of controllers so it's nice to have this as I don't have to worry about booting up just to find out my controllers are dead because I forgot to charge them.If you're someone who is not easily prone to eye strain or VR fatigue and you don't have a spare set of controllers but want to stay playing longer, then yes I'd say this is just for you. If you're someone who plays on and off throughout the day, or maybe tests stuff in VR and doesn't want to have to remember to charge their controllers every day or two, then yea this might be for you too.It's not a perfectly solution in my opinion but this is a much cheaper alternative than buying another pair of controllers (I spent around $70 ish total including taxes/shipping for the straps and the two batteries I use).

Only thing to note is despite the product image, it doesn't come with its own battery included

They work great for what they are designed for. Comfortable, relatively easy to strap on, fit my lipstick batteries snug without movement, and the provided cables are perfect length. Recommended for any long sessions that you need extra life from without having to sit down and charge.