Digger – Hinged Spiral Nail types has internal grooves onto which the specially
designed Spiral nail fasten onto the casing pipe. Collars are hinged at two places 180 degrees apart and one spiral nail in each half is driven between collar and the casing. It can be latched on the casing pipe without having to be slipped on. These are most effective where low annular clearance is encountered. The spiral nail gives a firm grip to the stop collar and when tested as per API 10D-2 Specifications they provide high holding force.