Model 1690 Bench Top Expander The 1690's compact design allows it to fit on your benchtop while the foot pedal gives you hands-free operation. Quickly and easily size muffler nipples and pipes. The 1690 comes with the tooling shown above for expanding capacity from 1-1/2" to 3-1/2". Additional tooling gives you expanding capacity from 1" to 5-1/2".