1. Look at the shell material, the market main switch brand general choice PC material, PC material also called bulletproof Rubber, anti-impact, high temperature, not easy to change color.
2. See contact point, is the switch process of conductive parts contact point. Contact one to see the size (the bigger the better). At present, there are three main contact points, silver-nickel alloy, silver-cadmium alloy and sterling silver. Silver-nickel alloy is currently the ideal contact material, conductive properties, hardness is better, also not easy to oxidize rust.
3. Look at the structure, through the appearance and feel to judge.