C&F Design Micro Slit Foam Waterproof Large Fly Fishing Box CF3500, Black Review (2026)

Who the CF3500 is built for

This box suits anglers who fish streamers, salmon flies, stoneflies or bass bugs and want a genuinely waterproof case rather than a splash-resistant one, since C&F Design markets it specifically for large flies that need real protection from moisture and impact. Its roughly 90-fly capacity across two facing micro slit foam panels gives enough room for a meaningful streamer or bass bug rotation without the box becoming unmanageable to carry. Anglers who already own other C&F Design boxes will appreciate that the foam inserts are interchangeable with other C&F cases of matching dimensions, letting you customize or replace foam without buying an entirely new box. Anglers who mostly fish small dry flies and nymphs will find this box oversized and better replaced with a slimmer case built around smaller slit spacing.

Build, dimensions and the micro slit foam explained

The CF3500 measures about 197 by 42 by 114 millimeters, or roughly 7.8 by 4.5 by 1.7 inches, and weighs 215.5 grams, close to 7.6 ounces, figures that are consistent across multiple retailer listings for this box. It is built with two facing panels of what C&F Design calls Micro Slit foam, arranged in three rows on each side of the case, with small holes molded into the foam to help you locate each slit visually before inserting a hook. The key advantage of micro slit foam over standard slotted foam is that it is designed to hold the sides of a hook's shank rather than having the hook point pierce straight through the foam, which the manufacturer states helps the foam resist wearing out even after repeated use. The case itself is described as 100 percent waterproof and finished in black, built from a durable outer shell meant to protect flies from both moisture and impact in a pack or vest.

Loading flies and caring for the box

To load a fly, you press the hook shank into one of the micro slit foam rows rather than driving the point all the way through, using the small locator holes molded into the foam to find each slit by feel or by eye. Because the box is genuinely waterproof rather than water resistant, it holds up well to being dunked or rained on in a wading jacket pocket, though it is still worth checking the seal periodically for wear if the box sees years of hard use. Dry the box out fully before long-term storage if it has taken on any moisture internally, and avoid overloading the foam rows beyond a comfortable fit, since crowding slits too tightly can accelerate wear even on foam designed to resist it. Because the foam inserts are interchangeable with other C&F Design cases of the same external dimensions, a worn insert can eventually be swapped rather than replacing the entire box.

How it compares with other waterproof fly boxes

In the site's waterproof fly box guide the CF3500 ranks first of eight, ahead of the Dr. Slick waterproof box with a slit foam insert, which scores 8.6, and several Aventik, Kingfisher and Maxcatch waterproof boxes that cluster around 8.4. What separates the CF3500 from that group is the micro slit foam's specific hold-the-shank design, which C&F Design positions as more durable over time than conventional slit foam that flies pierce straight through, along with the box's interchangeable insert system shared across the C&F lineup. The trade-off is price: this box costs noticeably more than the budget waterproof boxes it outranks, and its roughly 90-fly capacity is smaller than some rival boxes built with tighter, smaller slit spacing for higher counts. For anglers specifically carrying large streamers and bass bugs who want a box built to last, the CF3500's construction quality explains its top position in the guide despite the smaller fly count.

Verdict and who should consider a cheaper box

Choose the CF3500 if you fish large streamers, salmon flies or bass bugs and want a genuinely waterproof box with foam engineered to resist wearing out over years of use, especially if you already own other C&F Design cases and want matching, interchangeable inserts. Its roughly 90-fly capacity and 7.8 by 4.5 by 1.7 inch footprint make it a substantial but not oversized addition to a pack or vest. Anglers on a tighter budget, or those who mainly fish smaller flies where a higher compartment count matters more than shank-holding foam, should look toward the less expensive waterproof boxes it outranks in the guide. For dedicated big-fly anglers who want durability over raw fly count, the CF3500 remains a strong, purpose-built choice.

Frequently asked questions