I have a fairly hefty wooden calendar 2.5kg (5.5lbs). It has two hanging key slots in the back to hang it from. The keys are about 5mm wide on the narrow bit with a depth of 10mm.
I want to hang on my wall which is breeze block with about 15mm plasterboard over it.
I'm not useless with DIY and will be able to hang it myself, but I just don't know what hardware I need to put in the wall with the mix of materials etc...
Hope you will be able to help/advise.