Push-fit fittings are the fastest way to make a plumbing connection. No soldering, no crimping, no special tools -- just push the pipe in and it locks. They work on copper, PEX, and CPVC. The trade-off is cost ($8-$15 per fitting vs $0.50 for a copper elbow) and the fact that some plumbers don't trust them for permanent, behind-wall installations. We use them constantly for accessible repairs and emergency fixes.