Designed for permanent pipe grid installations in studios and theaters. Joins 2 overlapping pipes together in a 90 degree joint. Grooves act as a wrench holding the nut from turning while installing. Installs with a hex key tool in a battery drill. Fastens any combination of 1-1/2" pipe (1.9" OD), 1-1/4" pipe (1.66" OD), and 2" OD Tube. (Tight fit on 2" OD tube).