Laws of badminton about shuttlecocks by BWF

 BWF (Badminton World Federation) has written some rules about shuttlecocks:


2.1 The shuttle may be made from natural and/or synthetic materials. From whatever
material the shuttle is made, the flight characteristics generally should be similar
to  those  produced  by  a  natural  feathered  shuttle  with  a  cork  base  covered  by  a
thin layer of leather.
2.2 The shuttle shall have 16 feathers fixed in the base.
2.3 The  feathers  shall  be  measured  from  the  tip  to  the  top  of  the  base  and  each
shuttle  shall  be  of  the  same  length.    This length  can  be  between  62  mm  and  70
mm.
2.4 The tips of the feathers shall lie on a circle with a diameter from 58 mm to 68 mm.
2.5 The feathers shall be fastened firmly with thread or other suitable material.
2.6 The base shall be 25 mm to 28 mm in diameter and rounded on the bottom.
2.7 The shuttle shall weigh from 4.74 to 5.50 grams.
2.8 Non-Feathered Shuttle
2.8.1 The skirt, or simulation of feathers in synthetic materials, replaces natural feathers.
2.8.2 The base is described in Law 2.6