Waxed cotton clothing is great because it keeps the wet out even when the outer fabric is dirty, unlike modern "tech" membranes.  That's why its a great choice for working in environments where theres likely to be mud and dirt.

This kit provides you with all the products you need to reproof and then maintain any waxed garment.

You get two large bars of Otter Wax fabric wax.  One bar should be enough to reproof an XL jacket so this gives you enough for multiple or larger projects.

Normal washing of a waxed garment isn't really advised as it will just strip off the wax and you'll have to start the waxing process from scratch each time.

In the kit you get a 2oz bottle of canvas cleaner.  This is a Castille based solution that is perfect for spot cleaning any particularly dirty areas.  You also get a 2oz bottle of Odour Eliminator.  This is design to be sprayed on to the inside (non-waxed) of a garment to combat any smells.  It has a cedar/woody smell and works a bit like Frebrez in that it traps odour molecules.