Espressif offers their popular ESP32 line of RF transceivers, as well as eval kits for them. When ordering these parts you might find them sporting unexpected affixes in their part numbering, such as the ‘H’ in ESP32-C3FH4or the ‘X’ in ESP32-C3FH4X. What do these digits call out?
Per Espressif, the ‘H’ in these numbers indicates a higher-temperature part rated up to 105C. The ‘X’, on the other hand, indicates a part with a different pinout and pin count; ‘X’ parts have 18 I/O pins versus the typical part’s 22. The ‘H’ can safely be substituted for otherwise identical non-H parts, but the ‘X’ is not footprint compatible with non-X products.