There is No faster method for producing multiple mortises than with a template. And the accuracy achieved with a template is unparalleled these mortise bits are specially designed for use with templates, both linear and curved., if you've ever used a bushing with template work then you'll appreciate these bearing-guided bits; there's No need to calculate offset – Ever. Instead, the mortise is sized exactly to the template. And, unlike a bushing on the router sub-base, the guide bearing is always concentric to the cutting circle of the bit. This ensures precise cuts each and every time., #45590, diameter (D) 1-1/4, cutting height (B) 1/2, shank (D) 1/2, overall length (L) 2-5/8, replacement collar 47740, replacement bearing 47756, flutes 2, 45590 carbide Tipped Mortising 1-1/4 dia x 1/2 x 1/2 inch shank with upper Bb