We proudly use ISMI springs in all of our builds and component assemblies.  Over the years, we have spent a lot of time switching back and forth between spring manufacturers for our builds before finally making the decision to stick with ISMI.  The longevity and consistency of their springs has proven to be unmatched.
THE Guide rod adapter is designed to be able to utilize Gen 3 guide rods in Gen 4 and Gen 5 pistols.