SQ stands for super quite. It is Kubota's largest and quietest
generator. Special enclosures with a noise absorbing duct,
oversized muffler, extra-long air cleaners hose and quieter
cooling fan all add up to its super quiet performance. In addition,
the diesel engine that powers this unit produces far less soot,
HC and CO emissions. The advanced design and super engineering
minimizes both space and weight making it easier to transport.

Kubota SQ Series Generator Spec Sheet