Fittment:  GM C & K Trucks 1999-On For GM Part Numer 15733970, 15733971   Size:  Small Head Diameter: 18mm (0.71")  Medium Head Diameter: 26mm (1.02")  Flange Diameter: 30mm (1.18")  Stem Length: 24mm (0.95") 20x   Clips  an  order