Our Drop Style Transfer Cases use two gear sets that work together to create your overall gear ratio. The pre-installed lower gear set offers a 1.30:1 overdrive ratio that can be inverted to a 4.70:1 (7.80:1 in the Ultimate Drop model) underdrive ratio. The upper quick-change gear sets are available in your choice of over 60 different ratios up to 1.677:1 or down to 0.600:1 and can also be inverted to offer high and low gearing. To calculate your overall gear ratio, simply multiply the two together or contact us for assistance. Additional lower gear sets are also available via special order.