A magnetic strip with adhesive backing - use it to attach (non-permanently) items to a steel case.
12.5mm width, supplied in a length of 1 metre, can be cut with scissors.
This is a type A material. Both Type A and Type B will connect to steel magnetically, but if you need to attach to a non-steel surface (such as aluminium) then you will want to buy both Type A and Type B and attach one to surface, one to item. (As two Type A or two Type B will repel each other)