Danfoss ASV-PV + ASV-M automatic-balancing valve set, DN 25, OEM order code 003Z5688. The set pairs an ASV-PV 4G self-acting differential-pressure controller (setting range 5-25 kPa) mounted in the return with a ASV-M manual shut-off/measuring partner valve in the flow, connected by a capillary impulse tube. Together they hold a constant differential pressure across a riser or terminal-unit branch, so thermostatic radiator/terminal valves modulate without noise or flow starvation and the circuit self-balances under varying load. Supplied with factory insulation shells. Set (V) of ASV-PV, 5-25 kPa and ASV-M, DN 25, with insulation. Genuine Danfoss part; data quoted verbatim from store.danfoss.com (code 003Z5688). OEM P/N 003Z5688, EAN 5702424614744. HS 8481.80.