One of two traditional leash attachment options we offer on every Lundquist longboard. The through-box leash routes the leash string through the single fin box itself, leaving the deck and tail completely free of visible hardware.
What It Is
A through-box leash is a leash attachment point built directly into the bottom of the longboard fin box. A small resin-lined hole is drilled through the lower face of the single fin box. A leash string is threaded through that hole from the outside; the knot seats inside the fin box, hidden from view. Your leash clips to the exposed loop just like it would to a standard plug.
No plastic on the deck. No visible hardware on the tail. Just a clean surface and a leash string disappearing into the fin box.
Why We Offer It
Aesthetics. A longboard tail is one of the most visible surfaces on the board. Dropping a modern plastic plug in the middle of that real estate breaks the flow. The through-box leash preserves the clean lines that define a classic longboard shape.
Heritage-correct. This is one of the two ways longboard leashes were attached in the late 60s and early 70s, before plastic leash plugs became the industry default. If you're riding a log with a period-correct finish, the through-box method looks right.
Durable. The resin lining turns the hole into a smooth, high-strength pass-through. There's no plug to pop out, no gasket to fail, and no plastic to yellow in the sun.
Serviceable. The leash string is the consumable. When it wears out, pull the old one and thread a new knot through from the bottom. Takes 30 seconds and no tools.
How We Install It
The process happens after the fin box is glassed in and fully cured:
- Drill a pilot hole through the bottom face of the fin box, angled slightly toward the tail so the string exits cleanly.
- Over-drill and fill with resin. The pilot gets opened up to create a resin reservoir, then filled with tinted or clear resin flush to the fin box surface. This becomes the wear sleeve for the leash string.
- Drill a smaller finish hole through the center of the resin fill once cured. This is the actual passage the leash string threads through — the resin walls protect the foam underneath and give the string a hard surface to bear against.
- Thread the leash string up through the finish hole from the outside. A figure-eight or overhand knot at the top catches against the inside of the fin box and locks the string in place. The knot sits inside the fin box interior, completely out of sight when a fin is installed.
- Trim the string to your preferred loop length and double it back on itself for the leash cuff to clip onto.
Through-Box vs. Glassed Leash Loop
Both options are traditional, plug-free, and look right on a classic longboard. The short version:
- Through-box leash (this guide) — hole drilled through the fin box, string threaded through, knot hidden inside. Nothing visible on the deck or bottom. Requires a drilled and resined passage in the fin box.
- [Glassed leash loop](/build-guide/glassed-leash-loop) — small fiberglass loop glassed onto the deck near the tail during the lamination process. No plug, no hardware — just a small fabric loop sitting proud of the deck for threading the leash string through. No drilling into the fin box.
Neither is better than the other — it's builder and owner preference. Both are offered on every Lundquist longboard in the Board Builder.
When We Use It
Through-box leashes are an option on every Lundquist single-fin longboard and glider: Black Pearl, Salt Burn, Lunada, Dutchman, Spectre, Legacy, Magic Carpet, Fantasma, and every other longboard in the lineup.
We don't use through-box leashes on multi-fin boards. Shortboards, twin fins, mid-lengths, and thrusters get a standard leash plug near the tail.
The Takeaway
If you want the cleanest possible tail on your longboard — no hardware visible anywhere, not even a small loop on the bottom — the through-box leash is the option for you. Select it in the Board Builder when ordering, or if you'd rather go with a visible glassed loop on the bottom, choose the other option.