This allows for greater flexibility in the plumbing design. Reassemble and relocate the split pin in the slot provided. Allows for greater flexibility in the plumbing design. The valve allows air to be drawn into the waste pipe when negative pressures occurs.
It solved my problem, I needed a compact trap to avoid cutting drawer away under my washbasin. Sadly there is a warning not to use drain cleaners of any kind to avoid damaging the rubber reed valve. That part part is not available as a spare so would necessitate a whole new trap! Also if you drop anything down the drain (eg an ear ring) it is gone forever!