Nail guns use fasteners mounted in long strips (similar to a stick of staples) or collated in a paper or plastic carrier, depending on the design of the nailgun. Some full head nail guns, especially those used for pallet making and roofing, use long plastic or wire collated coils. Some strip nailers use a clipped head so the nails can be closer together, which allows less frequent reloading. Clip head nails are sometimes banned by state or local building codes. Full Round Head nails and ring shank nails provide greater resistance to pull out. Nailers may also be of the ‘coil’ type where the fasteners come in wire or plastic collation; the advantage is many more fasteners per load, but at the expense of extra weight. Industrial nailers designed for use against steel or concrete may have a self-loading action for the explosive caps, but most need nails to be loaded by hand. Nail guns vary in the length and gauge (thickness) of nails they can drive.