Works well jeff, I've got about 5 cans left from last year. Its silicon-based (like an alien lifeform from StarTrek?) and is great for doing a quick intermediate reproof of textiles and tents. Do it outside though, I inadvertently waterproofed my lungs the first time, and stunk the house oot!
Another thing I found is apply it to your textile jacket or whatever (outside, not a windy day!) and lightly rub the surface you have just sprayed with a plastic bag or similar, it seems to coat it better, leaves fewer porosities.
Porosities. Por-os-I-ties............Is that a word? Seems strange when you say it. I like it though.
And how come I'm talking like Mr f-ing silicon spray expert all of a sudden? Pull yerself together, man, Gassoon!
Time for my sleep now, nursey says!