Herm Sprenger Chrome Plated Ultra-Plus Prong Training Collar with Snap-On Latch (3.0 mm x 16" Girth) 1-Unit Heavy Gauge. Collar Measures 3.0 mm Thickness x 18-Inches Girth. The links can be removed to adjust size, you could also add more links. Chrome Plated Ultra-Plus Prong Training Collar with Snap-On Latch Latch features a unique, quick release snap that can be operated using only one hand. The patented center plate construction and symmetrical prong placement provide a natural contact for optimal communication.