RSJ is the name of Lange's best-selling ski boot models - ask any store and they'll tell you. Lange RSJ is what ski instructors and trainers call "real" children's ski boots, i.e. boots that promote improved ski skills for younger skiers. Lange has been developing RSJ for many years and has focused on the right angles, correct liners, durable metal buckles and an overlap construction that allows children to put them on and take them off themselves. Despite all its great qualities, the price is not high - yet the second hand value remains high year after year. The RSJ 50 has a slightly softer flex and is available in 17.5 to 21.5 with three buckles while the 4-buckle RSJ 60 is suitable for slightly older children and is available from 19.5-26.5 with type A adult standard starting from 22.5 (remember to match the bindings!).