Riblets are prepared by butchers by cutting a full set of spare ribs approximately in half. This produces a set of short, flat ribs where the curved part of the rib is removed and gives them a more uniform look. Loin back ribs don't always have this removed. When not removed they have a rounded look to them and are often referred to as baby back ribs. Another product (imprecisely) called riblets is actually the transverse processes of the lumbar vertebrae. Riblets used to be thrown out by butchers, but have become popular due to their excellent flavor and lower cost.