4 Pair 3/6"-1/2" x 6" Precision Parallel Block Set Gage Gauge Tool Set 4 Pair 3/16" - 1/2'' x 6'' parallel set Accuracy 0.0003"; within 0.0001" allowance ; To be used in setting up work for drilling and milling Contents include:1 Pair 3/16" x 1" x 6" with 5/16" hole.;1 Pair 3/16" x 1-1/4" x 6" with 5/16" hole. 1 Pair 1/2" x 1-1/2" x 6" with 1/2" hole. ; 1 Pair 1/2" x 1-3/4" x 6" with 1/2" hole. Quantity: 1 set (4 pair, 8 pieces); Plastic case over dimension: 8''L x 7''W x 2-1/2''H