Heckler & Koch / Umarex CO2 Magazine for H&K USP Tactical GBB Pistols

"I didnt buy this specific product, but I got the USP that came with it. The mag is absolutely amazing! It's durable, heavy, and won't break on you at all. The only issues I could come up with is it's somewhat difficult to line up the cap to screw the CO2 cartridge in, but it's not bad once you get the hang of it. I haven't ever had issues with it, and I've owned the gun and mags for about a year and a half.

Pros:
Very heavy
Durable
Easy to load with BB's

Cons:
Hard to get a CO2 cartridge into it, but it will get easy after a few tries.
VERY wide mag. It's pretty wide, but what do you expect for a USP mag?
Price!! These things are really expensive for what you get. Yes, they are amazing mags, but I think $30 to $40 would be better for what you get

"These mags are good but could be better. They don't leak like the other guy said but they do leave a lot of space between the bbs. I wish the would of made an extended version of the mag but the 18 rnd capacity works. They work great but could be better

"The mags what they need to do but the only real issue I have with them is that, it is very easy to mess up the threads on it. (broke two of them doing this)

"Well, these mags... Aren't the best.

I bought 1 extra, and both leak. One leaks out the entire co2 within seconds, the other leaks slowly until you shoot the gun a couple times. Seems like there's an issue with the output valve, which evike does not stock.

I've contacted the manufacturer, with no response, but I'll try again before I waste another $40 on a replacement.

However, the construction of the metal seems good, but the bbs stack with lots of space between.