Very strong magnetic clasp which is designed to be use with leather straps or similar materials that can be glued in. 

Each size measures:

 Internal size 5mm x3mm: 19.3mm (L)x8.0mm (W) x6.5mm (Thickness)

Internal size 8mm x3mm: 22.8mm (L)x10.0mm (W) x5.4mm (Thickness)

Internal size 19mm x5mm: 25.2mm (L)x12.2mm (W) x7.3mm (Thickness)

Internal size 13mm x4mm: 25.3mm (L)x15.0mm (W) x6.4mm (Thickness)

Internal size 15mm x3mm: 20.1mm (L)x17.6mm (W) x6.2mm (Thickness)

Please keep away from young children, they may kill if children swollow them.