Bath plug with drain valve

My shower is over my bathtub. I like to plug the drain whilst showering to retain the water to simultaneously bathe my feet. This gadget saves me fumbling for the old plug. Just leave it in the bath drain outlet receptacle and open/close it with a super easy two finger 45° turn of the rotary vane valve knob.
Fully clockwise is valve open. Fully anti clockwise is closed.

This fits both my bathtub or my kitchen sink. Both have 42mm outlets. I expect it can be scaled up or down a little to fit different size drain outlets. It’s intended to have small clearance to be a snug drop fit into the receptacle. No need to push it in as with a conventional tapered rubber plug. If it’s tight into the receptacle, it will distort the vane assembly and prevent proper sealing and vane valve rotation.

EDIT: I just added a smaller version of the plug which fits my washbasin outlet which is 35mm. So the 3 files which are prefixed with S- are the smaller set matching the 35mm plug hole. I had to red