Heavy duty aluminum I-beam Replaceable vial assemblies Red interior & finished aluminum edges HD-24 and HD-36 is 6-vial - Size:1-1/8" x 2-3/8" HD-48 is 6-vial - Size:1-1/8" x 2-7/16" HD-72 is 10-vial - Size:1-3/8" x 2-9/16" HD-72 will not fit sands PLC72 level case 24"