This is a universal screw cap and stopper set which will fit all standard waterbeds. It has been sold, tried and tested thousands and thousands of times.
The screw cap has 2 grips, as shown in the photo, to help pull it out from its socket in the mattress.
The stoppers sometimes get lost when the bed is filled or conditioner is used. The grips on the screw cap sometimes break off to leave sharp edges which could damage the bed. In this cases a replacement set is needed.