If a Jordan curve σ has a one-sided conformal collar with "good" properties, then, using the Reflection principle, we show that any other conformal collar of σ from the same side has the same "good" properties. A particular use of this fact concerns analytic Jordan curves, but in general the Jordan arcs we consider do not have to be analytic. We show that if an one-sided conformal collar bounded by σ is of class A p , then any other collar bounded by σ and from the same side of σ is of class A p .