This hop up rubber is prone to over hopping your bbs, killing your groupings and ripping when combined with large outer diameter inner barrels (like airsoftgi's line of tightbores). I strongly recommend avoiding this. Complete waste of money, my KJW 1911 and HFC VSR 10 stock buckings are far better in performance.
-Its red (favorite color)
-It has an interesting inner chamber design to maximize one's compression (You'd have to use it to understand what I'm talking about)
-The piece that holds it in place in Marui based hop up units is oddly shaped and doesn't do its job
-Material is very prone to ripping
-Will not work with 'fat' inner barrels
-Since it ripped on the outside I can't see this lasting long in high fps setups
-Over hops bbs in my KJW 1911 as well as killing accuracy
-Completely incompatible with my HFC USR 11/VSR10 and made the accuracy even worse
-The neat inner chamber that helps create awesome compression I believe also messes up the bb's flight path if it isn't seated correctly and cause erratic behavior such as over-hopping or spewing the bbs in random directions killing accuracy.
-Eventually useless as it ripped even though I didn't even remotely force it
Rating: [1 of 5 Stars!]