Sizing and specification
Three steps to a model
First: how the material sits
On a rack to be moved whole: jacking. On a pallet to be forked: an autonomous forklift. In totes to be placed in shelf cells: a tote robot. Handed across from a conveyor: roller transfer. Carrying your own superstructure: an extensible chassis.
Second: what it weighs
Size on material plus carrier, with 15–20% in hand. Running permanently at the limit wears drive wheels and the lifting mechanism faster.
Third: whether the site takes it
Three dimensions decide most of it: aisle width (can it pass and turn), lift height (can it reach) and entry clearance (under the rack, or the pallet pocket). Fail these and the datasheet is irrelevant.
Also check
Doors and lifts; floor flatness and slope; complete WiFi coverage; cleanroom, explosion-proof or low-temperature requirements.