Copper Fitting 1-1/8 to 5/8 (HVAC Dimensions) Reducer / Increaser Copper Coupling & HVAC – 1 to 1/2 (Plumbing Inner Dimensions) 99.9% Pure Copper - 10 Pack w20h20 Actual Filter Size – 31

Actual Filter Size – 31 3/4"w x 13 3/4" x 1"

+ Product Details Size – 18"w X 26"h is the size for the duct opening measurement only

Actual Filter Size – 25 3/4"w x 29 3/4" x 1"

+ Product Details Size - 34"w X 20"h X 2"d (for duct opening measurement only)

+ Product Details Size – 12" X 24" is the size for the drywall opening measurement only

Copper Fitting 1-1/8 to 5/8 (HVAC Dimensions) Reducer / Increaser Copper Coupling & HVAC – 1 to 1/2 (Plumbing Inner Dimensions) 99.9% Pure Copper - 10 Pack w20h20 Actual Filter Size – 31How 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