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

"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.