Attwood Pontoon Storage Blocks 4 Pk. These Attwood Pontoon Storage Blocks come in a pack of four blocks and are made of high-density, engineered composite. This stable design will keep your pontoon hull dry and off the ground. Great for fall and winter pontoon storage! When not in use, these blocks easily stack together for storing. Features Each blocks has a 4,000 lb. capacity Lightweight Easy to use Will not absorb moisture Dimensions 13-12 x 13-12 x 9-12 California Residents WARNING Cancer an