The magnetic check valves were magnetic actuation and minimal pressure drop.They meet the highest standards and only quality materials are used.They are fully compatible with fluorocarbon refrigerants and associated oils such as R11,R12,R22,R123,R125,R134A,R402A,R402B,R404A,R500,R502 & R507 etc.Feature ID. connection sizes from 1/4" through 2 5/8" Hermetically copper body Magnetic actuation 30 mesh screen to protect seat surface from debris Arrow indicated direction of flow Minimal pressure drop