Izwi rekuti "chubhu ye3/4 inch" rinowanzoreva dhayamita yekunze (OD) yechubhu. Kuti uone dhayamita yemukati (ID), unoda rumwe ruzivo rwakadai seukobvu hwemadziro. Dhayamita yemukati inogona kuverengerwa nekubvisa kaviri ukobvu hwemadziro kubva padhayamita yekunze. Hazvigoneki kuziva dhayamita chaiyo yemukati yechubhu ye3/4 inch usingazive ukobvu hwemadziro.