Length Comparator : Alpha Chem is manufactures,exporter & suppliers Length Comparator. Length Comparator : Used to measure the length variations of mortar specimens after autoclave soundness tests. The top beam is adjustable to suit the specimen’s length. Length Comparator, as per IS: 4031 with Dial gauge 0.01 x 10 mm Length Comparator, as per IS: 4031 but with 0.002 x 5 mm Dial gauge Available With Dial Gauge And Digital Dial Gauge.