Reviewing as a trans man/micropenis haver:Generally electric pumps aren't recommended for guys with my anatomy, but with some modifications and care, it can be used safely and effectivelyThere are 3 rubber seals of varying sizes that help create a perfect vacuum seal around my junk, even though the chamber itself is obviously too big for me. The pump is effective enough that I usually have to switch to the larger sizes of seal while pumping.The chamber and vacuum attachments are a standard thread, so they're compatible with most other branded pump pieces. You can easily mix and match for your needs- so I've been using a smaller chamber I ordered elsewhere. I also suggest using a pump hose with its own release valve and pressure gauge for safety and accuracy - but if you are very experienced with how pumping feels and where your limits are, this is less necessary but still important in the long-runThe pump charges quickly and battery life lasts multiple sessions. Pump's functions are a bit rudimentary- you have to hold down the power button to turn it off (which can accidentally increase vacuum pressure if you're not careful.) Thankfully, it has a release button to quickly reduce pressure just in case.The vacuum pump itself seems water resistant, but not water proof. I've used it in the shower (out of the stream of water) and it works, though I can hear water droplets sputtering through the vacuum. The other components can be used in the bath just fine.Comes with a bunch of little bonus items- various rings, protectors, small bottle of lube, and even a fl*shlight-type toy that (I think) is supposed to go inside the pump. Haven't figured out how that works, have just been enjoying it on its own hahaCannot attest to long-term size increase, but it's absolutely effective in the short-term for helping me get and maintain bigger and harder erections that I wouldn't be able to achieve normallySIZE NOTE: This pump likely not work for you if you are under 2"/5cm girth, 1.5"/3cm lengthI would suggest this to someone who is on a budget but has moderate experience pumping, as the pump is pretty powerful. Definitely pay attention while using it, lest you be sucked up into another dimension.5 stars!