Depending on the field of application magnetic stripe cards are offered in two classes:
Hi-Co (High Coercivity)
High energy in encoding (2750 Oe); low susceptibility to magnetic influences.
Cards with Hi-Co magnetic stripes are strongly protected against unwanted deletions. Strong magnetic field that can erase a HiCo card can not be found in our everyday life.
Lo-Co (Low Coercivity)
Low energy when writing (300 Oe); vulnerable to data loss due to magnetic influences (magnetic closures, etc.)
This magnetic stripe has a lower magnetic density, therefore cards with Lo-Co magnetic stripe can be effected by other magnetic fields easier. If a LoCo magnetic stripe is deleted by exterior magnetic fields, the card can be re-encoded.