These inserts fit into the 50mm Axminster SK100 O'Donnell Dovetail Jaws. Held in place by four cap head screws they are relatively quick to fit. These inserts change the gripping range of the 50mm jaw to that of the 25mm O'Donnell jaw. The 25mm insert expands into a 35mm dovetail recess and contracts onto a 21mm dovetail or 16mm spigot. The Axminster chuck offers an external grip between 30mm and 46mm, internal dovetail 18mm to 34mm and spigot 11mm to 24mm. Made from stainless steel to protect against corrosion. These can only be used in conjunction with the 50mm O'Donnell jaws. These jaws are suitable for Clubman and Evolution SK100 chucks and the Evolution SK114 Chuck.