The “Offset Arm” is a component of the sex machine that is attached to the rotating motor shaft, and provides one or more connection positions for the First Drive Arm. Each point of connection sets a different stroke length for the machine, based on its distance from the center of the motor’s shaft.
Many Orgasm Alley machines offer you to option of a discretely variable or infinitely variable offset arm at the time of purchase.
Discretely Variable offset arms provide several individual threaded holes to which the First Drive Arm may be attached. For example, a common 5 position arm will have 2, 3, 4, 5, and 5-1/4″ options. The advantages of this style are that it never slips and that positions are easily repeated.
Infinitely Variable offset arms provide a slot along which the pivot point of the First Drive Arm may be freely positioned. One loosens the pivot pin, slides to the desired location, and tightens again. The advantage of this style is that very small changes can be made to the stroke length.
Which style is right for you? I believe most people are better off with the Discrete Variable offset arm, primarily because you can quickly and reliably set a desired stroke position. If you are using dildos in the more extreme sizes, Discrete is also a better choice as more stress makes slipping more likely. If, on the other hand, you are interested in stretching and increasing penetration limits, the fine adjustability of an Infinitely Variable offset arm will help meet this goal. Most people can also get slightly more stimulation without discomfort with infinite variability.
When in doubt, select the Discrete Variable Offset