Fortunately I can freely adjust my SIM card size;

When I recently got a new SIM from my provider (Elisa Finland) it was a kind of multicard; the whole thing is about the size of a credit card used in the very first GSM phones in the 90's.
The card contains progressively smaller and smalled cards in push-to-pop-kindof frames, and you can go back to the larger format SIM by inserting the smaller one into the one-step-larger frame.

Hmm. I am not sure my explanation makes any sense but it is a fact; I can use the same card either as a micro-SIM or normal SIM.