Auto Bondage Ice Ball Lock - 70 mm ball made of stainless steel, the ice castle works on the principle of melting ice. This is perfect for auto bondage. Simply fill it with water, insert two sticks to allow excess water to escape. Then place it in the freezer. There is a hole in the outer tube that prevents the lock from being burst by frozen water. Capacity is approximately 250 ml. The duration of captivity depends on the ambient temperature; the lock opens at a temperature of 20 °C after about 2 hours and 30 minutes. The two loops at the ends are for attaching ropes.