Fitting Tube Dia: 13mm/0.51 Inch If the inner dia is small, you can use hot water to soak up plastic fittings, then dry them with paper towels, and then slowly install metal tubes If the inner dia is large, you can wrap tape on the metal tube (not included) First round the iron pipe with white paper. Then mark it, and then spread out the white paper to measure its length. Finally, get its circumference and divide it by pi (3.1415) to get the diameter

Fitting Tube Dia: 13mm/0.51 Inch If the inner dia is small, you can use hot water to soak up plastic fittings, then dry them with paper towels, and then slowly install metal tubes If the inner dia is large, you can wrap tape on the metal tube (not included) First round the iron pipe with white paper. Then mark it, and then spread out the white paper to measure its length. Finally, get its circumference and divide it by pi (3.1415) to get the diameter