This fin box requires gluing to the bottom of your board or kayak. It will fit a standard fin and includes a threaded insert to put a bolt into or slide the fin back and use a standard square nut and bolt found  on most center fins.
Note: This fix box will fit our efin, but it is a tight fit. It may require a light tapping to insert into position. The center fin bolt that comes with our efin will not thread into the permant nut in the channel. You will need to get a thinner screw or just use the square nut and screw that comes with the efin. See last photo.
 
Be carefull not to force or tap on the part of the fin where the fin bolt goes through, it can break.
Be careful not to tap or push on the propeller guard as it could damage it.
 
We recommend HH-66 adhesive to attach. The plastic fin box comes with a precut vinyl piece that can go around it and be glued to the fin box and board providing more surface area for adhesion.
Note: Adhesive is not included.