Ignore the 3-star review...
This DOES fit a Gen4 pistol BUT you need an uncaptured guide rod (for Gen3 pistols) and reducing ring, both of which Brownell's sells. I have used this setup for years in my Gen4 pistols and it works flawlessly. If the previous reviewer read the information correctly, he would see that the "current production" refers to the 17# weight of the spring. Don't trash companies by leaving garbage reviews for an EXCELLENT product you don't understand. Wolff springs and ISMI springs are great choices.
