Patent for an improved, simple, and inexpensive nut lock that can be easily used and removed. It lengthens the life of the bolt. The invention is "a bolt with a longitudinal groove or slot in which fits a tongue or lug on a washer which is provided with a notch or notches into which may be forced a portion or portions of a washer made of bendable material, opposite portions of which are designed to be forced into notches in the faces of the nut and thus the nut and both washers are bound or held firmly together" (lines 14-23).