The maximum length we recommend and offer is 15 feet to prevent keyboard functionality issues for common keyboards. If the cable is too long then the keyboard may not be detected or the LEDs won’t properly illuminate.
Some keyboards need more power which requires a shorter cable length to make the keyboard function properly.
The following keyboards are known to require more power which will require a shorter cable (7 feet):
HHKBs, Input Club’s K-Type, Massdrop’s CTRL/ALT/SHIFT, Ducky One 2 Mini