Classification:
Boiler double 1/2(4min) inner wire high temperature valve 
Inner wire 1/2 (4 points) to 1/4 (2 points) high temperature valve 
Inner filament 1/4(2 points) to 1/4(2 points) high temperature valve 
Boiler double 1/4 (2 points) internal filament high temperature valve 
Boiler double 1/4 (2 points) to 1/2 (4 points) valve
 Double 6-point internal wire high-temperature valves 
Double one-inch high-temperature inner wire valve 
4 minutes inside to 4 minutes outside high-temperature ball valves 
Double 1.5-inch internal wire valve