"Light weight pistol striker greatly reduces recoil and improves velocity. Stock weight 76 grams, delrin sleeved weighs 40 grams. Kit includes striker, drive spring, spring guide, and installs in minutes. Testing provided an average of 25 fps increase. Fit the following: ARIAKON 1.0 and 2.0, THE CORE, P.T. PROFESSIONAL, and ZEUS G1 and G2."
-Quoted directly from the manufacture's web-site.
The Alamo City Paintball Delrin Sleeved Lightweight Sistol Striker is older, so while it may be available used and in a few cases new, it is not commonly available anymore.