These plastic side bites are basic, yet quality, replacement fins designed to flank the center longboard SUP fin in a 2+1 SUP fin set-up. Come as set of two.

No matter if you're flat water paddling or SUP surfing, or a little bit of both, it will pay great dividends to give some serious consideration to what fins you're using. Most low-end SUP boards come with only a single, generic, cheap plastic long board fin. Upgrading your fins is the easiest way to really transform the performance of your stand up paddle board, and with a couple sets of fins you can suit your board for great flat water paddling one day and SUP surfing another.

Often times lower end SUP boards don't even have more than one fin box so your options are limited. Most high-end SUP boards, and especially paddle surfing boards, will have flexible fin configurations such as a 5-fin configuration. At the very least, most surfing SUPs should have a 2+1 fin box configuration, which will let you set up your board as a thruster (3 larger, equal size fins), a 2 + 1 (larger longboard fin in the middle with smaller side bites on the sides), or just a single longboard fin configuration. For flat water paddling, the most important concerns are typically drag and tracking. For surfing, there are a lot more variables and choices to suit the different preferences of SUP surfers.

The first thing you need to determine is what type of fins will fit in your board. The center fin box on all SUPs is a standard longboard fin box. Any longboard fin, regardless of the brand will fit in these center boxes. The flanking fin boxes are another story. These will either be Futures SUP Fins boxes or FCS fin boxes, and you have to get the same brand fins as you have boxes so youre choices are set by how your board was manufactured. Fins are removable, so you can swap out one style of fin for another, so long as you stick with the correct brand on the side fin boxes.

When it comes to SUP surfing, there are lots of SUP fin options to choose from:

• Longboard single fin set-up
• Classic 2 + 1 SUP fin set-up (also called tri-fin set-up)
• Thruster fin set-up
• Twin fin set-up
• Quad fin set-up

Often times with one small change, you can dramatically affect the performance of your stand up paddle board.

For stand up paddle boards, for the time being, Futures Fins are clearly the better fin system. While their fin technology is cutting edge, this has less to do with their actual fins than it has to do with their fin boxes. In contrast to FCS fin boxes, which are installed after a board is glassed, Futures Fins are installed pre-glassing. The Futures Fins boxes have a flange around the box that serves as an anchor point adhering to the glassing layer (similar to how a kitchen sink has a flange that sits on and adheres to the counter top). FCS fin boxes, alternatively, are two little pillars that are inset into the board post-glassing a hole is cut and the plug is put in. On surfboards, the FCS boxes span the thickness of the surfboard and attach to the top and bottom of the board. Unfortunately, on stand up paddle boards (which are far thicker), the FCS anchor pillars just sort of float in space in the foam. Its not an ideal design, yet you'll find these types of FCS fin boxes on an alarming number of SUPs because FCS has been around a longer time in overseas manufacturing. On our Tower stand up paddle boards, we insist on using Futures Fins boxes in our manufacturing and incur extra costs to do so to ensure greater product durability.

Futures Fins also seat into the fin boxes a little differently. The box they fit into is basically a box with a catch point in the rear. You slide the fin base into this box around the catch and then rotate the front down into the box. A front screw secures the fin base. When fully seated, the result looks similar to a glassed on fin. Alternatively on FCS fins the fin box is two attachment points. The FCS fin base is two prongs that fit into these two boxes. A side angled screw secures each attachment point separately. The result is a fin that sits on top of the board a bit and isn't always flush, and thus can potentially snag stuff in the water. While FCS is unquestionably the pioneer in modern day detachable fins, this isn't a great design.