well, the spec from the site, 1- piece inner thrust core with reverse scooped air inlet for smooth, kick-free operation. Improved accuracy through consistant shot to shot velocity and muffled sound signature. Soft centered inner core provides optimized ball-in-breech placement for centered feedstack and seemless feeding. Detent slots designed to work in perfect harmony with Kila Instinct TM Ego/Etek magnetic detent systems and stock rubber nubs. It almost gets rid of kick and much easier on detents i find, its super light as well.