Just an interesting thought, from what I understand. When ordering a service kit for an Aqualung reg, they send all the o-rings for the entire series of regulators, because it is cheaper to have one kit with everything than separate kits with just the o-rings needed. My LDS has three gallon size ziplocks of new o-rings from the unused o-rings from the kits. My daughter works there in the summer and in down times often sorts these to bins or specific sizes.