X-Series washers from this company are designed to secure bolts so that they do not undergo spontaneous loosening due to vibration and dynamic loads. The washers feature an exclusive spring effect that protects against slackening due to settlement and relaxation. These washers come in pairs, with cams on one side and radial teeth on the opposite side to secure the bolted joint with tension instead of friction. The washers also create an elastic reserve in the bolted joint to compensate for the loss of preload and prevent slackening. — Nord-Lock Inc., Elk Grove Village, Ill.