This kind of magnets have a strong adhesive on the back that allows you to glue these adhesive magnets onto various surfaces, especially cardboard and paper. The hot-sellers' dimension of block adhesive magnets include:

20x10x1mm, 20x10x2mm, 20x10x3mm, 20x10x4mm, 20x10x5mm

25x10x1.5mm, 25x10x2mm, 25x10x3mm, 25x10x4mm, 25x10x5mm
30x10x1mm, 30x10x2mm, 30x10x3mm, 30x10x4mm, 30x10x5mm

40xx20x1mm, 40x20x2mm, 40x30x3mm, 40x20x5mm

60x10x3mm, 60x10x5mm

We will gladly help you to choose the right magnet and advise you personally.