Zinc plated steel. Square keys have smooth corners for easy insertion into keyways. Handy kit for shop toolroom or toolbox. On hand when needed saves time and money. Plastic compartment box is easy to store. The Precision Brand 58-piece machinery key Assortment contains: (3) 1/8 x 1/8 x 3/4 in, (3) 1/8 x 1/8 x 1 in, (5) 3/16 x 3/16 x 3/4 in, (5) 3/16 x 3/16 x 1 in, (5) 3/16 x 3/16 x 1-1/4 in, (5) 1/4 x 1/4 x 3/4 in, (5) 1/4 x 1/4 x 1-1/4 in, (5) 1/4 x 1/4 x 1-1/2 in, (5) 5/16 x 5/16 x 1-1/4 in, (5) 5/16 x 5/16 x 1-1/2 in, (5) 3/8 x 3/8 x 1-1/4 in, (5) 3/8 x 3/8 x 1-1/2 in and (2) 1/2 x 1/2 x 1-1/2 in.