The flange size follows iso-kf standard, they are commonly used to make connections between iso-kf fittings and rubber vacuum hoses. The iso-kf flanges are often called quick flange fittings because they are quick to assemble

Specification:

Product name: flange barb adapter
Model: KF25-25
Material: 304 stainless steel
Flange size: KF25
Barb (fit hose inner diameter): 25 mm/ 1 inch
Overall Size: (Not Included Plastic Cap):40 x 40mm / 1.6" x 1.6"(Max D*H)
Main Color: Silver Tone
Weight: 103g

Package Content: 1 x Flange Adapter, 1 x Plastic Cap