MRS w/ Braided Air Line 42 InchDescription MRS from Polarstar is a 3 inches tall compact regulator which threads directly onto the HPA tank. This solution eliminates the need for a separate UFA and keeps very low air rig profile. It contains integral on off valve what is characteristic to this model and makes it different from the competitors. This enables you to depressurize the system before disassembling it from the tank to avoid wear and possible damage on the tank o ring and