Stroke Length and Bore Size Limitations

[MrForbes]

Yes, there are limitations, please see the Pneumatics Manual, and refer to these Robot Rules as well
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<R89> In addition to the pneumatic cylinders provided in the Kit Of Parts and the “free” pneumatic cylinders available for order through the Free Pneumatic Components Order Form, additional air cylinders or rotary actuators may be used. All cylinders, regardless of source, must be identical to those listed on the Free Pneumatic Components Order Form (e.g. same part numbers). Any additional air cylinders must source from Bimba or Parker Hannifin, or be recovered from prior year FIRST Kit Of Parts.

<R90> Items specifically PROHIBITED from use on the ROBOT include: Any air compressor other than, or in addition to, the one provided in the Kit Of Parts. Pneumatic cylinders and actuators different from those in the Kit or found on the Free Pneumatic Components Order form, with the exception of those specifically permitted by Rule <R89>.
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the free cylinder sizes are listed here

http://www.bimba.com/FirstFree.aspx