at the most commonly used angle. The sled is normally guided by a runner fastened under it that slides in a miter slot. This device is normally shop made, but can be purchased. Tenon jig: A tenon jig is a device that holds the workpiece vertically so cuts can be made across the end. This allows tenons to be formed. Often this is a purchased item, but it can be shop made. The tenon jig is guided by a miter slot or a fence. Stacked dado: Saws made for the US market are generally capable of using a stacked dado blade set. This is a kit with two outer blades and a number of inner "chip breakers" that can be used to cut dados (grooves in the workpiece) of any width up to the maximum (generally ). Stacked dado sets are available in diameters of . 8- and 10-inch stacked dado sets are not recommended for saws with or less. Although 10-inch stacked dado sets are available with a bore, these are recommended with a bore. Inserts: Table saws have a changeable insert in the table through which the blade projects. Purchasable inserts are usually made out of metal. Zero-clearance inserts can be made of a sawable material such as plastic or wood. When a zero-clearance insert is initially inserted, the blade is raised through the insert creating the slot. This creates a slot with no gaps around the blade. The zero clearance insert helps prevent tearout by providing support for wood fibers right next to the blade thus helping to make a very clean cut. Other inserts can be bought or created in the same manner, such as a dado insert. Splitter: A splitter or riving knife is a vertical projection located behind the saw blade. This can be a pin or a fin. It is slightly narrower in width than the blade and located directly in line with the blade. The splitter prevents the material being cut from being rotated thereby helping to prevent kickback. Splitters may incorporate pawls, a mechanism with teeth designed to bite into wood and preventing kickback. Splitters can take many forms, including being part of the blade guard that comes standard with the saw. Another type of splitter is simply a vertical pin or fin attached to an insert. Splitters are available commercially or can be made from wood, metal or plastic. Anti-kickback