the Sig short trigger is not a pull lightening modification. it just has a lower profile than the factory trigger allowing those with smaller hands to get a better grip on it and use more leverage when pulling, especially in DA. the following i know is applicable to the 226 and 229 models. other models may vary. unload your Sig. (remove magazine and bullet from chamber) field strip. remove take down lever. (rotate clockwise while pulling outward on it) pull trigger to release spring pressure and remove barrel locking block. (there is a small wire spring on it, do not lose) "passenger side" grip cover shown removed above. remove this spring: push trigger pivot pin out and remove slide catch lever. pull trigger up and out and remove trigger bar. install trigger bar on sig short trigger in reverse order. reassemble in reverse order. take note that the trigger pivot pin has a side with a slot in it. have the slot on the "driver's side" of the pistol w/ the slot facing parallel to the slide rails. on this pin there is a side w/ some flat grooves. they must be on the down side. note disassembly of pistol was done with short trigger already installed. i decided to make this EDU for OT:WMD after i had put it in a couple weeks ago.