Fixers are the smallest size of fasteners. They are normally 24 to 22 gauge (0.60 to 0.71 mm diameter) and generally have no head. They are used for attaching beadings, mouldings and so forth to furniture, etc. Lengths are normally in the range 10 to 32 mm (3/8 to 1¼ in) although some specialist manufacturers supply up to 50 mm (2 in).
Brad Nailers are 18 gauge (1.22 mm diameter) fixing guns. These fastenings are used to fix mouldings but can be used to used in the same way as the smaller 22 to 24 gauge fastenings. Their greater strength leads to their use in trim carpentry on hardwoods where some hole filling is acceptable. Whilst most 18 gauge brads have heads, some manufacturers do offer headless fastenings. Lengths range from 16 mm to 50 mm (5/8 in to 2 in).