It's NIX lice treatment, you'll want the 2 oz (59 ml) bottle, mix with one gallon of water to create a 0.5% permethrin solution. You can treat the enclosure with it, just use a clean spray bottle to lightly mist the enclosure, paper towel, and hide (not the water dish!!!), allow everything to dry, and put the snake back into it.
Some people treat the snake with it, but I don't recommend it as people often overdo treatment and then the snake suffers from permethrin poisoning. My vet also didn't recommend it, he said to use a spray like Reptile Relief or just one drop of dish soap in water while they soak is enough to kill off the mites.
ETA: If you get the NIX you'll have enough solution to treat your current snake enclosures and rack as a preventive.