CPR 3000 Component. One O-Ring for 2.1 Airframe [PML-CPR3K-OR-2.1]. LOC / PML : Canadian retailer of Estes, Aerotech, Quest, Rocketarium, Madcow, Public Missiles, Aeropack, LOC Precision, PerfectFlite, Jolly Logic, rocket engines/motors, launch supplies and electronics