Good haul!, that mini belt sander type attachment things are seriously crap IME, really not even worth the hassle of setting up.Amazon mini belt sander for angle grinder attachement.
For a mini these are good & controlable belt and take bugger all space, find I use it a lot for quick little jobs.
Probably 5x cost of the attachment thing, but ended up binning the one I had as it was such a faff and rubbish.