Hornady Steel Match features the same bullets and powders as traditional Hornady ammunition, but features a polymer-coated steel casing instead of brass. The end result is the same reliability and performance from normal brass-cased ammunition at a fraction of the price, due to the lower material cost.
Hornady Steel Match ammo is designed to be used in high-volume competitions, when shooters often aren't permitted to pick up their brass as they go through the stages. Instead of leaving all that money on the ground, shooters have the peace of mind that their casings aren't the most important part of the match, their scores are.