The 561-5 from Taco is a 3/4” Sweat 3-Way Zone Valve. It's a 3-way bypass version of the 571-2 zone valve. Typically used to control the flow to a fan coil or terminal heating unit.
 

Features:

• Proven Performance & Dependability – Millions in Use. Taco Zone Valves are the Industry’s Top Choice for Consistent Performance.
• Silent Operation.
• Replaceable Twist Off PowerHead allows to service the valve without removing it.
• Unique Construction Ensures Positive Shut-off and Leak Proof Operation.
• Easy to Install.
• Manual Open (Bypass) Lever.
• 24 VAC Powered with Isolated End Switch.
• 100% Factory Tested.
• Made in the USA.
• 3 Year Warranty for PowerHead, 5 Years for the Valve Body.

 
Technical Specifications:

• Connections: 3/4" Sweat (C x C x C)
• Max pressure rating: 125 psi
• Max operating temperature: 240F
• Min operating temperature: 40F
• Flow range (GPM): 4.5 - 6
• Cv: 6.1
• Voltage: 24V
• Amps: 0.9