Very straight forward insert, should fit well in most messenger style bags. Using mine in a army surplus paratroopers bag (with some velcro to hold it in place. Nicely fits camera with attached lens, a second lens and a flash - although I may remove a couple of stitches to set the camera a little lower in the insert. Insert fits the bag without making it too bulky.
The biggest issue is the bottom of the insert has no padding what so ever. There is just fabric to keep your goodies in the insert. If using in a bag with out padding on the bottom you will need additional padding for the bottom.