Sadly for me, I'm only in the Milestone (40) at the moment. I might start working on Slayer legit tomorrow to get some charms and raise that bad boy up. Then I'd be in the 60's. only need Sum, Farm, RC, Herb up for 70's. Oh boy.
They came out with or around the time that Max capes and Completionist capes came out. Pretty much the jist of is; If you have every skill over level, lets say, 50; You're allowed to wear Milestone cape (50) and under, but not 60 until you have all skills over 60. I think you can make them with 5 balls of wool on a loom (Like in Falador), But I could be wrong on the making part; check the wiki.