The new MK11 EVO/R105 is a simple, rugged and reliable air delivery system. The MK11 EVO is a compact balanced diaphragm first stage with a forged brass body fitted with thermal fins and protective plastic bumpers to ward off scratches. The R105 delivers smooth, dependable air flow from its classic downstream valve design. Built to last, the R105 features a durable metal valve housing and an anti-scratch front cover.