Great quality springs. These springs are great. I have never worn out a spring till I got into competitive & defensive shooting. The instructions for cutting the spring to length is on the package. If you have a pair of wire cutters and a tape measure with you, you can replace you spring anywhere. 

Simple replacement you just need to trim to length.  I like to make them about 10 inches past the end of where the tube would be if assembled.  I recommend getting the NC follower to go with this.  Nordic Components makes some nice stuff.