[ariadne]

Hi - I've used a 90 degree plasting fitting ("elbow") to allow the tubes to join vertically so they dont kink at the connection under clothes.  Helps you be less of a peep show and maybe keep warmer.
 4mm internal diameter fittings available on ebay.  But you also, ideally need a small piece of fairly rigid polyprop 4mm tube to join the end of the fitting to the cup itself.  Use very hot water to help get the rigid tube carefully onto the cup end without breaking anything.  Pics attached
A

           

[Man2Woman]

Hi - I've used a 90 degree plasting fitting ("elbow") to allow the tubes to join vertically so they dont kink at the connection under clothes.  Helps you be less of a peep show and maybe keep warmer.
 4mm internal diameter fittings available on ebay.  But you also, ideally need a small piece of fairly rigid polyprop 4mm tube to join the end of the fitting to the cup itself.  Use very hot water to help get the rigid tube carefully onto the cup end without breaking anything.  Pics attached
A

Good idea. Looking good.