Mike AA, I'm pretty sure that I bought the 1 1/4" the first time, but bought the 1 1/2" the second. The diameters listed are for max use, you can put smaller hoses in and they will constrict down to the size needed. The larger size makes installation easier. The tape I use is Versachem 82110 WrapIt 1" x 10' Repair Silicone Tape. I originally bought at my local hardware store but I like it so much and found so many uses that I bought a 10 roll pack on Amazon for a considerable savings.