Length comparators measure length changes of hardened cement paste, mortar and concrete prismatic specimens. Indicators are mounted on a sturdy upright support attached to a solid triangular base. All units Include stationary and movable anvils designed to fit GAM-8700 gauge studs, which are cast into test specimens and an invar reference bar. Unit accommodates test specimens up to 4" x 4" (102 x 102mm) cross section. ASTM C151, ASTM C157, ASTM C227, ASTM C311, ASTM C341, ASTM C342, ASTM C452, ASTM C490, ASTM C596, AASHTO M210, AASHTO T107, AASHTO T160