Cheap Leecraft BK-1 Blank Phenolic Sheet Review
From the Integra Tooling website (appears they are the manufacturer), the following information is provided:
BK-1: Universal Blank Table Saw Insert 15" L x 11" W x 1/2" H
BK-2: Universal Blank Table Saw Insert 15" L x 11" W x 1/4" H
There are also BK-3 (3/4") and BK-6 (3/8") sheets available.