Before revision: By not using the elastic o-rings, the claims are that the wires freely slide through the slots without friction but this is incorrect as it simply allows more rotation or tipping of teeth (and therefore some potential loss of precision of movement) before the bracket edges contact the wire resulting in friction.
After revision: By not using the elastic o-rings, the claims are that the wires freely slide through the slots without friction but may not be correct as it allows more rotation or tipping of teeth (and therefore some potential loss of precision of movement) before the bracket edges contact the wire resulting in friction.