I use the LowePro S&F Filter Pouch 100 and I'm not at all impressed with either the outer rigidity, no labeling accommodation and that the top flap doesn't seal the top as well as it could when closed. I do like that the top flap is otherwise well thought out - reverse opening, space to pinch the clasp closed - and I like that it has LowePro's sliplock clip on the backside. But that it is so flimsy is really unsettling and its use makes me anxious. For something that potentially holds over $1000 worth of delicate gear I'd like something a little more substantial.
If the Lee 10 Filter Pouch had a belt loop and space for the holder it would be the perfect solution. But, as it stands, the perfect 4x4(6) filter pouch has yet to be made.