All depends on the discs. They often label discs with the highest current speed even though they are capable of faster speeds. Fuji (Taiyo Yuden manufactured) has been using the same discs since 12X. When the 16's came out, they just stuck 16X labels over the 12 until they updated the packaging. When 24X became common, they did the same thing. They've been the same discs since the 12X world. Of course, some cheaper made discs may not work.