Pedestal trap 1-1/4 inch (bathroom wash hand basin size).
Especially suited for waste pipes that are directly under the basin.
1-1/4 inch BSP threaded inlet connection, compression type pipe outlet connection - suits push fit or solvent waste pipe.
BSP (British Standard Pipe Thread) sizes don’t match up with what you would measure using a ruler. Have a look at the BSPT link at the bottom of this page for more information about how plumbing threads are measured.