Polyform NF-4 Heavy-Duty Twin Eye 6.4" x 12.6" - Cobalt BlueNF 4 Heavy Duty Twin Eye 6. 4" x 12. 6" Cobalt Blue The NF Series Boat Fender features multiple ribbed, reinforced ropeholds, making it the strongest fender in its class. The NF Series is an extra tough recreational boating fender for smaller boats and a good choice for use in boat locks and tidal areas where fenders are exposed to high stress situations. The NF Series is designed to last and stand up in the toughest conditions, as well as being