TREC VITAMIN D3 + K2 [MK-7]. D3+K2 combination. This allows you to shape your strength and to prepare you much better for your next workout. D3 + K2 [MK-7] is an excellent composition of vitamins necessary for the proper functioning of the musculoskeletal system, which strengthen the skeletal system, support blood clotting processes, and also care for the muscular system.