Tire lever is the tool when using to install/remove the tire to/from the rim to help your power.
ATL comes with 3 pcs. It's made of forged light alloy to be super lightweight and durable.

The top section for hooking the tire bead is thin forged to enable to insert between the tire and rim easily. Also no sharp edge to prevent scratching the tube.

The handle part has a cut out for hooking the spoke to keep the tire bead removed.

The ordinary Q/O spec tire is made of rubber tire and wire bead. Wire bead is usually made of stainless steel or Kevlar. It works to hold the tire in the rim properly and stably by hooking the wire to the inside groove on the rim.
Wire bead diameter is always a little smaller than the rim diameter, therefore we need strong power to remove the tire from the rim, and it is usually impossible to do by hand only. Tire lever helps this job as a strong finger.

Wire bead diameter and rim diameter are all different. The tighter combination, the stronger power requires. Sometimes, a plastic tire lever gets broken. But metal tire lever like ATL is more durable than plastic one.