A thermal cycler system for use with a sample holder configured to receive a plurality of samples includes a sample block having an upstanding peripheral side wall and being configured to receive the sample holder and an adaptor having an upstanding peripheral side wall configured to be positioned about the peripheral side wall of the sample block. When the peripheral side wall of the adaptor is positioned about the peripheral side wall of the sample block and the sample holder is received in the sample block, the peripheral side wall of the adaptor extends in an upward direction toward the sample holder.