A cryostat microtome integrates a microtome mechanism within a refrigerated chamber. Classification depends on whether the combined unit is considered a microtome (87449) or a refrigeration apparatus with an ancillary cutting function. In practice, instruments marketed and used primarily for histological sectioning are generally classified as microtomes, but the refrigeration component may complicate the analysis; a binding ruling is advisable for high-value cryostats.

Both items can fall under 87449, but they should be listed as separate line items on the commercial invoice with distinct part descriptions. The HPLC detector module is a part for a chromatograph (originally 87442), and the microtome blade set is an accessory for a microtome—both converge in 87449 under the SITC structure. Accurate part descriptions and cross-references to the parent instrument support CBP review and help avoid delays.