#8 coil zipper is the standard heavy weight zipper available in the world. The width & thickness is 7.7mm x 3.1mm 
This is the most widely used zippers in all heavy applications. Only in most extreme cases, a #10 zipper is used for more safety and amity.
The standard applications are in all fields for luggage, Purses, Sleeping Bags Tests, Awnings, Wet suits, Leather garments. Leather goods, Coats, Textile jackets and many more applications.
This is popularly known as the leather zipper. Suits all applications precisely.
#8 Standard Cross-wise Strength Tests
#8 Brass: 115
#8 Aluminum: 65
#8 Nickle Silver: 120
The standard problems which people have with 38 zipper is that the edges are very sharp and hurt a lot & also they are hard in movement in one-way & require effort in the reverse two way zippers At 3k, we produce the smoothest two way zipper with relatively very smooth edges.
The B.S. 3084:2006 recommends that in coil which has to be used in specification A, B, C, D & E to have lateral cross-wise strength of 15, 20, 25, 37 & 47 kgs respectively. 3K satisfies this comfortably.
For details of British Standard & #8 zipper test charts, click here.
For wash Care instructions, click here.