Spike Cone Circular Barbell Stainless Steel Sizes: 16 Gauge (1.2mm), 14 Gauge (1.6mm), 12 Gauge (2mm) 10 Gauge (2.5mm), 8 Gauge (3mm) Length: 5/16" (8mm), 3/8" (10mm), 1/2" (13mm), 5/8" (16mm)