We carry three sizes, all have included fixed dividers along the length and removable/adjustable dividers along the width. We offer them because they work, are sized right for our bags, and are manufactured by fellow Americans. The Plano 500 works in: Most any pack or bag 9" wide. It can be a handy organizational tool to keep small stuff separated.  The Plano 1000 works in: River Bank Tackle Box x4, Canoe Thwart Bag x1, Canoe Seat Pad and Bag x1, Highway 1 Panniers x4 per side, Gladstone Tool Bag x3. The Plano 800 works in: Creek Bank Tackle Box x4.