Coloured tube cap to fit inside tubing with matching code number.
Available in 7 colours; Red, Yellow, Blue, Black, White, Green and Orange.

Tubing and fittings are manufactured to provide a good friction and maintain the outside diameter.  The Splines on the Male fittings accomplish a tight fit and prevent undesired oration yet still allow intentional turning. This feature permits cementing to be a final operation.
Whilst every effort has been made to produce these components such that the interface it must be understood that due to the difficulty in holding tolerances of extended tube, it may sometimes be necessary to drill, file or ream the tube selected to produce the required fit.