The Black Box Planetary gearbox is a gear reduction unit that fits between your existing transmission and transfer case. The Black Box can be shifted between 1:1 high range for highway duty and a deep 2.72:1 gear reduction when in low range. The Black Box is designed for the 4x4 enthusiast who is seeking significantly more slow speed control than currently available.
Going from a stock Vehicle or a single transfer case will be a massive improvement when adding a Blackbox to your 4x4. Remember the traction and control you gained when adding a locker or a new set of tires when you first started out. That is the substantial increase that you can expect when adding a Blackbox to your 4x4.
Operating a vehicle with the right gearing, RPM and wheel speed is key. Having your crawl ratio too low will have your engine revving, but if the reduction is too deep you may not be able to build enough momentum to pop over that rock face or ledge. On the other hand if your crawl ratio is too tall, or not enough gear reduction you will find yourself having less control. Leaving you no choice but to try and bounce off obstacles at speed. Having an extremely low crawl ratio isn't the key goal, The ideal 4x4 not only has low gears but has gearing options.