The Roller Derby Youth Quad Skate Replacement Bases in size J12 are designed for junior skaters looking for a vibrant and fun ride. With a wheelbase of 4.75 inches and a total length of 8.25 inches, these bases are compatible with Roller Derby FireStar and Roller Star models. They are a fixed size and NOT ADJUSTABLE.  Made in China, these bases feature a pink and teal color scheme that will surely stand out on the skate park. Perfect for young skaters looking to replace worn-out or damaged parts on their quad skates, these Roller Derby replacement bases offer durability and style in one package.  Fits Youth/Junior Size 12 (J12) boots.  Wheelbase 4.75 inches, total length of teal plastic base 8.25 inches, total weight for the pair is 2 pounds, 13 ounces.