We have used a Snapdragon Ocean Trek extra large spray skirt and a Harmony 38-20 with our Pakayaks and both work perfectly. By using those sizes you will be able to convert to almost any brand on the market. Seals brand 1.7 will fit an OUTER rim length up to 36″ and an OUTER rim width up to 20 1/2″. We would urge you to determine what type of spray skirt best fits your needs and then try them on to determine the best fit around your mid section. The “tunnel” should be water-tight yet not restrict breathing while under exertion. Best to go try one on and see which fit/feel the best on you in terms of comfort.