Not really bullet proof. But it's pretty darn rain proof. I keep my rain cover on my pack. But you could seriously almost entirely do away with rain covers with this stuff.

I inadvertently washed away the waterproof coating from the inside of my elderly Sierra West tent. After removing the remaining flakes & rinsing any debris from the outside body, I sprayed Nikwax Tent & Gear Proof over the entire outside of the tent including the fly. Amazingly water now beads on the fabric as good or better then when the tent was brand new. I repeat this process once every two years to insure maximum waterproof effectiveness. Great product.

This stuff sealed my tent water tight! After one treatment it has made water bead right off and that's been nearly 6 months ago. Maybe twice a year to treat, it's a cheap way to stay nice and dry!

Having this in an easy to use spray bottle is amazing. It works super well and is very easy to use. If you rain fly is losing it's repellent finish then use this stuff, it works very well.

used it on my 10 year old timbuk2 bag (i had some of my stuff soaked in the last rainstorm), and so far so good. water beads up and slides off mostly. the underside doesn't do so hot as far as the beading up, probably because it's gotten dirty from setting it down. but i haven't had any water leak through yet.

I use it on my very old backpack and on my old "not any more" rain jack. and go for 2 days trip on a very hard non stop rain and wind. and me and my gear stayed bone dry!!!
don't think, JUST BUY IT!!!