These depth skids are made by Northwest Passage Tools from 6061 T6 anodized aluminum. They can be attached to cast iron or steel No. 3, 4 and No. 4-1/2 planes made by Stanley, Lie Nielsen and others. The universal mounting rails have a 1 mm thick ledge and two magnets per side that provide consistent registration on the plane. The depth skids can then be attached to the mounting rails using the provided 10-32 stainless steel screws and washers. They make it possible to achieve precise thicknesses when planing stock that is too thin for power equipment. They are ideal for working with inlay, shoji/kumiko components, and other parts that need to be planed to a precise thickness down to a minimum of 1 mm (0.040").
For multiple parts, the thickness can be set using an existing component, set up blocks or gauge pins. They have a capacity up to 2" (50 mm).
These only fit flat sided No. 3, 4, and 4-1/2 bench planes made from cast iron, steel or other magnetic material - they won't work with aluminum or bronze planes.