Rocky Studded & Spiked Collar. The Collar Width 5cm Length 42cm (16.5) Diameter 11.5-13cm (115-130mm Please note: We have two grades of Faux Leather and they are âBeginners/Soft Bondage: This Faux Leather is light weight and designed for soft bondage play. It feels light to wear but is not suitable for hardcore/heavy bondage. The average thickness of the PVC Material is 2mm Hardcore/Heavy Bondage: This Faux Leather is thicker and stronger and designed for more experienced or hardcore bondage users. It is heavier to wear and more robust. The average thickness of the PVC Material is 2.5mm Choose the grade that is most appropriate to your use.