R clips with a double coil to give extra gripping strength on the pin. Use these with cotter pins. Sizes are 2.3mm to suit pin 9-11mm Dia. | 2.8mm to suit pin 11-14mm | 3.6mm to suit pin 14-20mm | 4.5mm to suit pin 20-26mm | 5.6mm to suit pin 26-34mm | 6.3mm to suit pin 34-45mm | 7mm to suit pin 45-56mm. See the chart for hole size of the cotter pin.