Brad Nails: Brad Nails come in a variety of lengths and thicknesses - 15 Gauge, 16 Gauge, 18 Gauge and 21 Gauge - Quite simply, the higher the gauge, the thinner the pin. Check the size your Brad Nailer. fires before purchasing. Here we feature 18 and 21 gauge finish nails in both galvanised and stainless steel. Click size/type to learn more. Unsure? then call 0333 8000 345. Or drop us a line