The Ruelco three way block and bleed pressure switches are the most reliable and simple pressure switches on the market. Using our unique base and piston system, the sensing range can be changed from 10-10,000 psi. with only the movement of an O-ring. This allows Ruelco pressure switches the versatility to change with changing system parameters. With additional bases the Sensing range can be extended from .5 psi. up to 20,000 psi.