This carbine kit is designed to convert your stock we galaxy into a super light and fun gbbr. This kit mounts using 3 screws where the top rail would usually be installed. Installation requires the removal of the rear sight which I initially didn't want but couldn't avoid as it is a very tight fit even without. The kit uses the stock top rail mounted with 3x m2 x 15mm bolts. when tightening them be sure not to overdo it as the screws could pass through and damage the internals of the gun (scratch bolt and hopup) so the use of washers may be necessary. The kit also allows the upper and lower to be separated for hop-up adjustment and it should be functional with all versions of the we-galaxy (hi-capa, Glock and 1911).