There are two types of tacks, Improved and Fine.
Improved Tacks have a thicker shank and a larger head and are used for fixing open weave materials such as webbing and hessians.
Fine Tacks have a smaller shank and head and are used for close weave fabrics.
Each type is available as100grm Handy Packs or 500grm Trade Boxes
6mm - 1/4" Fine Tacks are very small and only used for delicate work or for fixing fine fabric to thin plywood panels. (6mm Fine approx 400 nails per 100grm)
10mm - 3/8" Fine Tacks are used for fitting calico and lightweight top covers. (10mm Fine approx 325 tacks per 100grm pack)
10mm - 3/8" Improved Tacks have a slightly thicker shank and a larger head. These are used for medium weight top covers , scrims and bottom cloths. (10mm Improved approx 200 tacks per 100grm pack)
13mm - 1/2" Fine Tacks are for fixing heavy top covers, hessians, and webbing on lightweight frames.( 13mm Fine approx 280 tacks per 100grm Pack)
13mm - 1/2" Improved Tacks with their larger heads, are used for open weave fabrics like hessians, and webbing on lightweight frames. (13mm Improved approx 175 tacks per 100grm Pack)
15mm - 5/8" Fine Tacks are used when fixing thick layers of fabric. (approx 150 tacks per 100grm Pack)
15mm - 5/8" Improved Tacks are used mainly for webbing.(15mm Improved approx. 150tacks per 100grm Pack)