"Quick-edge" Hatch Trim for Mariner Kayaks rear hatch, black 

Sold as 4'6" long piece

If your not sure that your Mariner rear hatch originally came with this Trim read this:

Per Matt Broze:
Check if the kayak was sold by Mariner Kayaks directly or was it one made by NW Kayaks and bought through a NW Kayak dealer (those kayaks have a bigger rear hatch--and didn't use a secondary vinyl "Quick-edge" U-channel seal to firmly hold the fiberglass plate to the rim under the neoprene cover--The plate on the NW Kayaks was likely made of black plastic and was enough thicker than ours--and smaller than the hatch rim circumference that Quick-edge couldn't hold it in place well). The serial number of the kayaks we sold--and did the finishing work on, should start with MSQ; those NW Kayaks finished start with something like NWG (if my memory is correct). You should be able to find the serial number on the right side near the seam within one foot of the stern--and with Mariner finished models, anyway, in felt pen on a whitish reinforcing band on the underside of the deck in front of the cockpit.