mine also have wet and dry, only not cynoed, i have a slot the spats sit on and then the bolts tightened squashing the spats between large washers and the wet and dry.
unfortunately because the inside is cut [:@] they sit too low, not only for what i prefer as looks, but for the grass.
the sides also arnt strong enough. ok i did have a twist edge washer on before that cut through after a few landings. after the landings they've had i expected more strength, the joint for the two halves is extremely weak.
i'm going to lay a bit more cloth and epoxy inside, the amount that should have been in there the first time. ok they will weight a bit more, but they should last more than 5-6 flights now.
The spats are a must for the look, even if they are just £21 sacrificial items for that first good photo