Made of 304 stainless steel,Weak magnetism.
304 steel is often referred to as "food-grade" steel, as it is unreactive with most organic acids.
For guitars, exposure to organic acids is usually through perspiration and airborne moisture, and a good corrosion-resistant fastener is a good solution.
Brinell Hardness=300, Three times harder than ordinary metals.
keep away from screwloose,slip and rust.

The 13 Types(320pcs Total) as follow:
1.For fender style or standard pickguard, amplifier logo,backplates mounting screws, 50pcs.
3.For Neck Plate, 10pcs.
2.Metric Bridge Height,20pcs.
4.Tall and Short Humbucking pickup ring,40pcs total, per 20.
5.For Gibson Pickguard screws,50pcs
6.Humbucking pickup mounting with springs, 10pcs.
7.For Truss Rod Cover,20pcs.
8.For Enclosed small size tuning keys,50pcs
9.For Single coil pickup with cone shaped springs,20pcs.
10.For bridge mounting,20pcs.
11.Soap bar pickup mounting,10pcs
12.For selector switch mounting,20pcs.

These rich contents determine its wide applicability.