4208bc, 1/4 x 1/16 x 72, mill aluminum channel, designed for trim work, frame work and reinforcement projects, often used to fit a plywood edge where the plywood thickness matches the channel width dimension, channel width dimension is the first size specification listed in the size column, and is a fraction, aluminum is light weight, yet strong, withstanding heavy pressure and loads, aluminum can be bent or formed into a multitude of shapes.
