Double wax is quite simply a cob of half pure beeswax and half cobblers wax.
This way you will only need one cob in your pipe case, and it can be used for two different purposes.
Complete with a piece of leather to use as a hand grip.
This double wax cob is also formulated so that it will not melt into a black puddle in your pipe case as has been the custom in the past.
