The Ghost Edge 3.5Lb trigger kit fits all Glock models Gen1-4 (does not fit the g42/43). Includes the Ghost edge connector, 6lb trigger spring, 4lb firing pin spring, 6lb firing pin spring, and reduced pound firing pin safety spring. Great kit for reducing trigger pull and drag for increased accuracy and followup shots.
I bought 2 of these. One went on a gen 2 G17 and the other on a gen 3 G19. Both work just fine and have been through a couple classes. 1000+ rounds through each and no issue at all. Not sure if it is really a 3.5lb spring, but I love it over stock. I have a friend with a gen 4 G19 and it made his feel grotty and crunchy. Didn't work for him at all, but I love it on my 2 guns. Not sure if he did a poor install, neglected to clean his gun before install or just not very compatible with the gen 4s. Either way, I dig it. Add an extended slide release and it makes an awesome set up.