Interchangeable aluminum heating blocks provide excellent thermal conductivity and accommodate various Test tubes, cups, and plates. Depending on the combination of blocks selected, plastic spacers (36620-67) can be used to fill a half-width recess, ensuring optimal thermal performance. Most blocks come with a separate hole to accept a thermometer. Order a flexi-block to accommodate multiple size tubes, vials, or cuvettes at once. Unskirted PCR plates can be heated in either size flexi-block. Skirted microtiter plates, deep-well plates, and PCR plates can only be Incubated in the triple-width version. Precision-engineered aluminum heating blocks offer excellent temperature accuracy versatile range of interchangeable heating blocks work with many size sample tubes and plates. Heaters sold separately.