Here is #O56 Inverted centers imperf strip of 3 with missing OS. It also shows the guide marks at the right. No gum. Very good looking item to add to my collection of #101-113. I started my new collection of #101-113 after selling most of my 45 year collection of Liberia. It was time to think about cutting back on what i collect in Liberia. Does anyone have a copy of #O56 imperf inverted center with missing OS ?