M-Series Blocks are made from computer-machined aluminum, allowing for gentle, smooth curves. Combine extremely light weight with Schaefer's legendary quality and the result is an incredible strength-to-weight ratio. The machined aluminum side plates will outlast most blocks made of plastic or composite material. M-Series Blocks are available in a variety of configurations to fit any application. Use the M66 blocks for boats in the 35-45 foot range and the M82 blocks for boats in the 45-60 foot range.