Flexible Waste Trap - 1 1/4 to 32 or 40 mm - 1 1/4 bstp = 41.91mm (Approx) Usually used for Bathroom Wash Basins but may be used In other applications that use the same size. 1 1/4to 32 or 40 mm diameter (male spigot)( Quoted In Internationally adoptedB.S.P.T.British Standard Pipe Thread (Actual thread diameter is approx 1.650 or 41.91 mm(Approx) ) For example - 1 1/4 (5/4) Plastic nut with rubber seal at one end for connection to items such as wash basin waste connection. Other end connected to 32 or 40 mm female *Pushfit / *Solvent / Compression connector. Please note:Quoted In B.S.P.T. British Standard Pipe Thread (See below for more Info) The Unit supplied will be either the Alca or Goflex model. The two makes are almost identical however there may be some minor differences In moulding etc between the two.Main Picture shows the Goflex the two Technical drawings show the Alca.*(Diameter's quoted (3240 mm) are actual sizes**. Some other suppliers use slightly smaller or larger fittings but may still refer to them as 3240 mm so it is recommended that to be certain your fittings are compatible you measure the internal diameter of your fittings to ensure a suitable seal / Fitting will be achieved.*(Some solvent pipes use a larger pipe diameter so measure your pipe and fittings diameters to ensure correct sizing is used. Ours is quoted in actual sizes** i.e 40 mm is 40 mm. Also note sometimes the addition of extra glue can resolve small tolerance differences.**( /- some small acceptable tolerance) British Standard Pipe Thread is a family of standard screw thread types that has been adopted internationally for interconnecting and sealing pipe ends by mating an external (male) with an internal (female) thread.A list of 16 thread sizes are defined by the standards ranging from 116 Inch to 6 Inch. The size was originally based on the inner diameter measured in inches of a steel tube for which the thread was intended. This often causes confusion as people think the size refers to the outside diameter of the male thread.