The device is packaged in a through-hole TO-262 (I²Pak) with long leads, suited for board-level power switching where a solder-in heatsink or clip is preferred over a surface-mount footprint.
If you are qualifying a substitute, verify the package outline and thermal interface against your heatsink design.
At 31 A that is about 13 W of dissipation in the channel alone — well within the 80 W package limit, but the TO-262 tab must be heatsunk to keep junction temperature under 175 °C. Gate charge is 36 nC at 5 V, which is modest; a typical microcontroller GPIO can switch it at tens of kilohertz without a dedicated gate driver, though a series resistor in the gate path helps control ringing.
Package and mounting — TO-262 through-hole
The IRLZ44ZL comes in a TO-262 package (I²Pak variant with long leads), supplied in Tube form. It is a through-hole device intended for insertion into a PCB and soldered on the opposite side. The metal tab is the drain connection and provides the primary thermal path — a heatsink clip or a thermal pad against a chassis plane is expected for any continuous current above a few amps. The long leads give extra clearance for mounting to a heatsink that stands off the board.