Overview Product Description Type - Internal tooth lock serrated washers. Directions - For all Imperial bolts and screws. Genuine imperial sizes NOT metric equivalent. Sizes given are internal, Example 1/4" size washer will fit over 1/4" thread sized bolt. Product Videos Custom Field Product Reviews Write a Review Write a Review × Genuine Imperial serrated shakeproof washers zinc plated steel UNF UNC BSF BSW Rating * Select Rating 1 star (worst) 2 stars 3 stars (average) 4 stars 5 stars (best) Name Email * Review Subject * Comments *