Magnetic stripe cards can be classified into two groups: high coercivity (HiCo) and low coercivity (LoCo).

High coercivity magnetic striped cards are harder to erase, and are used in applications where cards are frequently used or need to have a long life. HiCo stripes are resistant to damage from most magnets or magnetic fields. Typical HiCo applications include: access control, time and attendance, and gift cards.

Low coercivity magnetic striped cards are easier to erase. They can be damaged by even a brief contact with a magnetic field. Typical LoCo applications include: hotel room keys and other applications where the card is only used for a short period of time.

HiCo cards can generally be identified by a black stripe, while LoCo cards are generally brown. The encoding technique is the same for both types of cards, except that a stronger electrical current is required to write on HiCo cards.

1_ Low-coercivity (loco) at 300 Oe or 600 Oe;
2_ High-coercivity (hico) at 2750 Oe or 4000 Oe.
Loco is mainly used for membership card, loyalty card, points card, etc; while hico is mainly used for bank card, access control card, hotel key card and some other cards which requires a higher security and complexity.

Basically, there are 2 widths for magnetic stripe;
1_ 8mm (2-track)
2_ 12.5mm (3-track)
12.5mm is the most frequently used width for magnetic stripe cards.