Abstract: A continuous, synthetic plastic plumbing trap comprising a generally U-shaped tubular structure having a first opening comprising an outer threaded annular rim, which is adapted to form a seal with an outer rim surface of a downstream tubular member, and an inner annular rim which is adapted to form a seal with an inner rim surface of a downstream tubular member, the inner and outer annular rims of the trap opening being so situated as to accommodate any tubular downstream member having a rim which fits between the inner surface of the threaded annular rim and the inner annular rim; and a second opening comprising a threaded annular rim, both said threaded annular rims being adapted to engage fastening means of the same size.