Product info: Nokia 8850/8890 ghost sim. - allows you to use two sim cards in one phone - no need to cut your sim card like with similar products - more convenient than removing your back cover/battery every time you want to swap sim cards - combine business/personal lines and address books on one handset - switch between networks easily - no more coverage problems! - sits inbetween your battery and back cover How they work: the 'sim card' from the product fits into sim slot on your phone whilst your two sim cards fit into the ghost sim. Your phone then operates as usual but allows you to switch between two sims without removing the battery and back cover first. To alternate between sims simply turn the phone off and on again.