Danfoss ASV-PV + ASV-BD automatic-balancing valve set, DN 25, OEM order code 003Z5697. The set pairs an ASV-PV 4G self-acting differential-pressure controller (setting range 5-25 kPa) mounted in the return with a ASV-BD partner balancing valve (presetting, shut-off, drain and two self-sealing measuring test plugs) 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. Set(V) of ASV-PV, 5-25 kPa and ASV-BD, DN 25. Genuine Danfoss part; data quoted verbatim from store.danfoss.com (code 003Z5697). OEM P/N 003Z5697, EAN 5702424614690. HS 8481.80.