Little Mac Valve

Little Mac Valve : 

A tiny but key component of almost every sort of bagpipe is a one-way valve that keeps air from backing up the blowpipe and thus allows the piper to take a breath while pressure and airflow to the pipes is maintained by squeezing the bag between body and arm. Called a "blowpipe valve" or "flap valve" the traditional form is a simple leather disk tied or tacked to the lower opening of the blowpipe so as to be hinged.