Hi Mark: The foam rows in C & F fly boxes are designed for certain hook sizes. I wonder if your brother-in-law was using an inappropriate size of hooks for the slits in the foam. Generally, the more rows of foam in the box, the smaller the flies and conversely, the less rows of foam the larger the hook. For example, the 12 row foam box (six rows of foam on either side)is for sizes 14-24, and here I am talking of the smaller size of box. I've had no problem with mine.
Neville Gosling Greater Vancouver, BC Bruce, My brother-in-law was thrilled with his box *two* summers ago. However, last summer he found that the foam slits had developed a memory and that the flies were quite loose. This made him pretty unhappy. Don't think that I'd get one as a result. Mark
