Match the torch to the current at your real duty cycle, not to the maximum figure on the power source. A 250 A torch at 60 percent is enough for sheet and short runs. On continuous welds above 300 A move to water cooling, because an overheated neck wears nozzles faster and heats the operator through the cable.
Check the connector. The Euro standard fits most machines, but Migatronic, Kemppi and some industrial machines use their own solutions, and water cooled torches add water couplings and a control lead. Give us the model of your machine and we will supply the torch with the right connector or an adapter.
Cable length affects wire feeding. Up to 3 metres a two roll feeder handles solid wire. Above 4 metres and with aluminium you need four rolls, a PTFE liner or a push pull torch with its own motor in the handle, because soft aluminium wire birdnests in the feeder.
For aluminium over short distances the simplest answer is a spool gun with a 1 kg spool in the torch. The wire then travels 15 cm instead of 4 metres and the feeding problem disappears. For mechanised work take a machine torch with a rigid body and a mounting thread, usually water cooled.