OEM part:
NTVC-005
Universal Black Gas Cap Breather Line Vent Cap (NTVC-005) by No Toil®. One way check valve that eliminates the need for a long vent hose on your gas cap. The No-Toil Vent Cap is an anodized, machined aluminum one way check valve that eliminates the long gas cap breather hose and gives your bike that special look to set it apart at the track or on the trails.