7/8 Inch (HVAC Outer Dimension) 3/4 Inch (Plumbing Inner Dimension) - Copper Long Radius 90° Elbow Fitting with 2 Solder Cups For Plumbing & HVAC – 99.9% Pure Copper - 10 Pack Black + Product Details Size –

+ Product Details Size – 16" x 32" or 32" x 16" is the size for the duct opening measurement only

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Durable Material - High Quality Shatterproof Rustproof plastic material with the strongest magnets for easy and secure attachment to your floor register

+ Product Details Size – 24"w X 30"h is the size for the duct opening measurement only

+ Product Details Size – 28"w X 10"h is the size for the duct opening measurement only

7/8 Inch (HVAC Outer Dimension) 3/4 Inch (Plumbing Inner Dimension) - Copper Long Radius 90° Elbow Fitting with 2 Solder Cups For Plumbing & HVAC – 99.9% Pure Copper - 10 Pack Black + Product Details Size –How to measure HVAC & Refrigeration tubing Refrigeration tubing is measured by it's outside diameter O. D: 1 4, 1 2, 5 8, 3 4, 7 8, 1 1 8, 1 3 8, 1 5 8, etc. Plumbing tubing is measured by it's inside diameter I. D: 1 8, 1 4, , 1 4, 1, 1 1 4, 1 1 2, 1 3 4,etc. Rule of Thumb: "HVAC" nominal tube sizing 1 8; larger than the same nominal size "plumbing" pipe. So for example, a 1 4" HVAC fitting, is the same as a 1 8" Plumbing1fitting. Or a 1 2" HVAC