Shakti Springs Inc. Offers Multi-tooth Lock Washers. Shakti Springs Inc. Is an ISO 9001 accredited organisation. The Multi-tooth Lock Washers are used with screw and nuts to effectively add spring take-up to the screw elongation and to increase the frictional resistance under the screw head or nut face. These are normally used where security of assembly is critical. The multi-tooth lock washer shall be made from carbon spring steel i.E. IS 4072-1975.