Size Selection Tips:
1. Measure the duct opening size, NOT the outside of the existing register.
2. Choose the register size that equals to the duct opening. Register sizing is based on the duct opening dimensions (Width x Height).
3. Outside measurement on each side will be about 1.75" larger in order to cover the hole.
4. DO NOT choose the register that equals to the outside measurement, it will be TOO BIG to fit in.