Precise Compatibility: 555-050RP Replacement power head fit for all Taco 570&550 series, including 555, 556, 557, 560, 561, 562, 571, 572 and 573 zone valves. Easy Replacement: Replace the zone valve power head quickly without draining the heating system. The 555-050RP offers a direct-fit design for Taco zone valves, ensuring a smooth and leak-free installation process.