Type A or type B?
Type A is thicker and protects more against heat, spatter and contact heat: the choice for MMA and MAG welding, flame cutting and gouging. Type B is thinner and gives more feel in the fingers, which is needed for TIG welding where you need to guide the filler material precisely. Besides EN 12477, values according to EN 388 and EN 407 are usually also listed on the glove.
Welding work needs more than gloves
Combine the gloves with flame-retardant clothing according to EN ISO 11611 and with a welding helmet or face protection with the right shade. Replace welding gloves as soon as the leather is hard or burnt: hardened leather actually conducts heat to your skin faster.