The new iPhone 4S, which Apple will promptly release to the public at 8 a.m. on Oct. 14, is a complete redesign from the iPhone 4, despite looking almost identical to last year's model. But for those who already own an iPhone 4, will those old cases still be compatible with the new model?

The good news is that most cases will work. The Verizon iPhone 4 reportedly has an identical button configuration to the iPhone 4S, so most of those covers should work fine. Only certain form-fitting cases will not accommodate the 4S model.

Apple's new iPhone 4S measures 4.5 inches tall, 2.3 inches wide, and 0.37 inches deep. The iPhone 4 and 4S have identical dimensions in height, width, and depth; however, the mute switch and two volume buttons have been slightly moved to accommodate for the new dual-antenna system. Comparing the models indicates the iPhone 4S has its mute button moved approximately 3 millimeters to the right, while the two volume buttons are only about 1 millimeter to the right.

Many companies have updated their inventories in the one week that's passed since the 4S unveiling in Cupertino, Calif. last week. Here we delineate which models will work with Apple's new iPhone.

The Apple Store shows the following cases are compatible with the new 4S model:

While not verified by Apple, these cases, according to their respective companies, promise to definitely accommodate the 4S model:

Unfortunately, the owners of these cases will most likely need to throw down for new cases come Friday:

Apple is taking pre-orders for the iPhone 4S on its website until its Oct. 14 release. Apple broke the record for most pre-orders in the first day, selling more than one million iPhone 4Ss. The previous record holder was last year's iPhone 4, which sold 600,000 units in the first day of pre-sale.

Most cases available on Apple's website range from $15 to $90. You can view them here.

If you buy an iPhone 4S on Friday and find your case doesn't fit with the new device, let us know in the comments below.

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