PHC - Magnets

2mm thickness is perfect for magnetizing Miniature bases for Transport cases 
(Which we also stock): Link

General Guide for magnetizing for miniature bases (using GW bases as an example):

25 to 28mm base - 3 x 2mm
32 to 40mm base - 5 x 2mm
40mm to 60mm bases - 10 x 2mm
60mm to 90mm bases -  15 x 2mm
Bigger than 90mm base - 20 x 2mm