Tuf glide is a dry film lubricant/rust inhibitor in a carrier of oderless mineral spirits. It comes in a plastic bottle of some sort, the small one has a needle tip applicator, larger ones are generally used to refil the small bottles or to "recharge" a tuff cloth. Tuff Cloths are tightly woven microfiber cloths that are pre-soaked with tuf-glide and come in a resealable foil pouch.
Use the tuf glide sparingly as using too much tends to make it pool around instead of quickly evaporating the mineral spirits, leaving the actual product behind. Tuf Cloths apply the correct amount with a single wipe, so they're quite easy to use. Marine tuf cloths use a different active ingredient, which apparently works much better at preventing rust.