Made in the USA, Dynabrade Contact Arm Assemblies provide superior belt tracking. All products are industrial-rated for tough production performance. For Air and Electric Models - 4" to 17" Workable Reach. All rubber Contact Wheels are 70 durometer, unless noted. Features and Benefits Dynabrade parts and dynabrade accessories are designed to work best on dynabrade air tools and last a long time 70 Duro Rubber Material Crowned Face Surface Notes Dynabrade 11321 - Contact Arm Assembly, 7/16" Dia. x 3/8" W, Rubber Wheel, with 1/2" (13 mm) W Platen.