Product circumference: 47cm
Shelf: Widest point: 13cm 
Smallest point: 9cm
Gap between shelf and the circle top: 30cm

Self assembly required. Comes flat packed with wall mounting kit, which includes: 
2 x shelf screws 
2 x shelf to wall brackets 
2 x dowels 
2 x plasterboard plugs 
2 x wall screws 

If your shelves are going into a thick brick wall, plasterboard plugs will not be needed.