644 - Smart Temperature Transmitter
H - Head Mount
A - Output: 4-20 mA with Digital Signal Based on HART Protocol
K5 - FM Intrinsic Safety Explosion-Proof Combination
J6 - Enclosure: Universal Head (Junction Box) Aluminum Alloy with 50.8 mm (2-in) SST Pipe Bracket (1/2-14 NPT Entries)
M5 - LCD Meter
F6 - 60 Hz Line Voltage Filter