# Choosing Between the Two Motor Gearboxes
When your application demands the use of one of these gearboxes, the right choice may not be entirely clear. Here are two key points to consider when making your selection:
* Form Factor - Which one of these will fit and mount comfortably in your use case?
* Gear Ratio - How much gearing flexibility do you need out of these gearboxes?
### 2 Motor Gearbox - Through Bore
This gearbox utilises two [NEO V1.1 Brushless Motors](https://www.revrobotics.com/rev-21-1650/), allowing the user to adjust the gear ratio by changing the pinion and cluster gear to 36:36, 24:48, 18:54, 12:60, or 10:60. (1:1, 2:1, 3:1, 5:1, or 6:1)
In theory, this can also be used for a drivetrain, but its benefit of a narrow profile opens it up for compact applications.
The output shaft is 1/2in Hex through bore, and the output gears have a MAXSpline bore. The motor plate contains two pairs of 2in pitch #10-32 tapped holes for mounting the REV [Through Bore Encoder](https://www.revrobotics.com/rev-11-1271/), and the output plate contains an array of holes for mounting to structure, as well as mounting as an input to the [MAXPlanetary](https://www.revrobotics.com/maxplanetary-system-kit/). The 5:1 Ratio (60:12) can be micro-adjusted slightly larger by swapping the 12T pinion with 11T or 10T.
### 2 Motor Drivetrain Gearbox - Through Bore
This gearbox utilises two [NEO V1.1 Brushless Motors](https://www.revrobotics.com/rev-21-1650/), and can be mounted in a variety of options, including flush with MAXTube or spaced away from the tube to enable both chain-in-tube and chain/belt outside tube designs.
Profiling of this drivetrain is more vertical while still allowing it to be out of the way. Weight distribution is also something to consider if you were to implement this gearbox.
The user can adjust speed by switching pinion gears on the motor between 10T, 11T, 12T, or can adjust wheel size by switching 2nd stage gear pairs. 2 Pairs of 2in pitch #10-32 tapped holes are available on output shaft for mounting the REV [Through Bore Encoder](https://www.revrobotics.com/rev-11-1271/), and mount holes for the gearbox are on the same horizontal plane as the output, set 4 inches apart. The output shaft is 1/2in Hex through bore, and the output gears have a MAXSpline bore.
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