Small: 3/8" (9.5 mm) diameter barrel with a 1/4" (6.3 mm) wide angle detail blade.Large: 1/2" (12.7 mm) diameter barrel with a 3/8" (9.5 mm) wide hollow ground blade.When you are looking to upgrade the quality of your swivel knife, the Craftool Pro is the one to choose. This stainless steel swivel knife is designed for a lot of regular use. The ball bearing swivel makes the contoured yoke turn smoothly, making it the perfect choice for the professional leather craftsman.