Overview The RoboCycler® temperature cycler is quite different in design than most traditional PCR machines. As such, it can be used with more applications than most other machines. The RoboCycler® has 4 temperature blocks. The first 3 blocks can be used for temperatures ranging from 25ºC to 99ºC, and Block 4 can be used for temperatures ranging from 6ºC to 25ºC. One of the blocks (Block 2) can even be programmed for a temperature gradient. This allows samples within the same run to be exposed to temperatures varying in the range of 45º to 99ºC or 35ºto 99ºC, depending on the model. Samples are moved from one block to the next via a rotating, robotic arm. Because of the movement from one temperature block to the next, it is not necessary for the machine to take time ramping like most PCR machines. This is a nice feature, because it saves time. An LCD screen on the front of the machine is used for setting up programs. The screen is easy to read, and the set-up procedures for programming the cycles are easy to follow. All information (such as time remaining, set temperature for the blocks, actual temperature for the blocks, and cycle number) is shown clearly on the screen. The RoboCycler® can hold up to 99 programs. Beyond that, it is possible to link up to 10 programs together to run in sequence. The instruction manual is quite helpful and gives detailed instructions for assembly and programming of the machine. The rotating arm has a heated cover, called the Hot Top, which fits over the tubes. This eliminates the need for an oil overlay. Our lab has one earlier model of the RoboCycler® which has a simple On/Off switch controlling the Hot Top. For some reason, the newer model is without this switch, requiring the user to press successive buttons on the front of the machine to toggle the Hot Top on and off if it needs to be switched during a cycle. This is only slightly more cumbersome, but the users in our lab still prefer the switch on the older model. The need for switching the Hot Top off and on only occurs with certain applications.