Hyvair DO3 modular sandwich stack valves mount right under directional control valves with the standard NFPA patterns. The rugged steel body design allows for high cycle and quick response applications. They have uniform height. Valve body thickness is the same for each series and provides a clean, neat, uniform appearance. This also reduces the number of bolt kits. Modular valving eliminates leaky connections, reduces plumbing costs and places controls together. Manifold mounted control circuits greatly reduce space requirements from conventional line mounted valves. Hand knobs with locknuts are provided standard.