Delta is Lone Star’s mid-tier plastic, sitting between the Alpha baseline and the Victor premium blends. Opaque and grippy. Thirteen moulds are listed in it.
That makes it the middle option: more lifespan than Alpha or Bravo, less than Delta 2, with a feel between them.
It isn’t premium. Delta discs still move with use, and Delta 2 is the stiffer, longer-lasting version.