For measuring Acme screw threads Leaves are made of corrosion-resistant stainless steel Convenient design: leaves swing out for use and fold away in holder for storage Leaf dimensions are approximately 1-3/16" to 1-3/4" long by 0.03" thick. Overall gage length is 3-1/2" 29 degree inch model includes pitch leaves 1 to 12: 1, 1-1/3, 1-1/2, 1-3/4, 2, 2-1/2, 3, 3-1/2, 4, 5, 6, 7, 8, 9, 10, and 12 Used for measuring inch pitch for Acme screw threads. Leaves are made of corrosion resistant stainless steel. Convenient design: leaves swing out for use and fold back away in holder for storage. Leaf dimensions are approximately 1-3/16" to 1-3/4" long by 0.03" thick. 29 degree inch model includes pitch leaves 1 to 12: 1, 1-1/3, 1-1/2, 1-3/4, 2, 2-1/2, 3, 3-1/2, 4, 5, 6, 7, 8, 9, 10, and 12.