A jetting unit pushes water through a nozzle that cuts through fat and scale and flushes it down the line. Rods with cutting heads do a similar job by hand where jetting would be too much for the pipe.
The pipe gets looked at before high pressure goes in, because jetting is the wrong tool for a cracked or collapsed run.
Say how old the blockage is, what has been tried and whether the drain serves a kitchen.
Galway cafes, pubs and restaurants see grease build up in kitchen drains, which usually needs jetting rather than rods alone.