This laser cut multimedia kit makes seven ( 7) HO scale model gate valves for the gas burners and cold blast main of the Walthers Blast Furnace model. The 4 smaller gate valves (approximately 0.31 inch diameter pipe) are designed to fit the gas burner pipes, one is an extra to use as you see fit. The 3 larger valves are sized to fit 1/2 inch tube for use on the cold blast main. Since the kit does not include cold blast pipes, the builder must provide them. One kit has enough valves to detail one Walthers Blast Furnace. The extra valve can be used as a spare, freight car load or installed on another industry as gate valves are common.