Recommeded for use with our MS-H-Pro Round Hotplate Stirrer (81112304) with Stainless Steel Hotplate. Made from anodized aluminum these blocks are ideal for heating and mixing solutionsin a variety of reation vessels/vials and small round bottom flasks. These reaction blocks have a pre-drilled hole to accommodate our PT-1000 sensor to measure the heat of the block. The containment ring holds the Quarter Blocks in place on the hotplate.