I read the Grin Factor details and it looks like a good product. I wouldn't personally buy it because:-
1. In the Youtube Videos they only use the sander in spots that have armour underneath it.
2. I would never buy from any business where I can't go back if there is a problem or concern.
3. I would not buy from any business that uses either aol, gmail or hotmail for their domain email. lol.
4. 100 British pounds for jeans and armour plus shipping plus duties. (1 Pound is 1.56 Dollars)
5. I think they just double the kevlar in key areas to make it 400gsm. We are in the process of upgrading to 320gsm which is the maximum thickness Dupont makes Kevlar in. So 400 is hard to believe for me.
At the end of the day it is your call. They look like they are well made but I wouldn't buy them because I have a hard time believing some of the claims being made. But that's just me.