An alpha unit for the PTC-225 Tetrad thermal cycler made by MJ Research, Inc., Waltham, Massachusetts in 1995. These are the sample block/heat pump modules in which are placed the vessels containing the DNA to be amplified. Serial no. AL004358.

DNA samples are placed inside this module to be amplified or copied. When attached to the rest of the machine, known as a thermal cycler or PCR, millions of identical copies of the sample can be produced within a matter of hours. The Sanger Institute in Cambridge, England, used this type of equipment for their work on sequencing the human genome. The Human genome project, which aimed to sequence the chemical structure of human DNA and identify the genes that determine heredity, was completed in 2003. The machine was made by M J Research Inc.