From GRN MNSTR:
Let Heartless up your ups. Heartless Wheels is the only wheel brand that is 100% designed, focused, and dedicated to the agiliity minded skater. Heartless Wheels feature a true hollow core hub (cap and core) with a 35mm narrow profile tire, that allows a skater to turn, carve, jump, and cut with unbelievable ease. We strictly focus on those roller derby skaters who look to gain the most agility and maneuverability possible. Heartless Wheels are available in 6 different hardnesses for a variety of options to suit your style of skating and the surfaces you skate on.