A 5.3mm diameter 'O' ring with an internal diameter of 139mm. Made from Nitrile (NBR N70) rubber which is ideal for use as a drive belt on larger 'V' pulleys. For our range of wooden, plastic and aluminium 'V' pulleys, use our 2.6 or 3.5mm diameter pulley belts. Suitable for use up to 70 Deg C.