The rigid and robust construction of the Groz range of knurling tool holders makes them ideal for countless knurling applications. Single knurl holders these are useful for light duty applications. They come complete with one straight knurl. Holder Size: 4 x 3/4 x 1/2 inch (100 x 19 x 13mm) Knurl Dimension: 3/4 x 1/4 x 1/4 inch (19 x 6.35 x 6.35mm)