The left-click is malfunctioning. Therefore, I'm selling it as junk. Those with knowledge may be able to repair it by disassembling it and replacing parts. There were times when it worked fine depending on Windows patch updates, but it's been acting up again recently, so I'm listing it. It might be a driver issue, though. There are no other models with high-speed scrolling besides this one, but it's costly to get another one, so I've decided to use a cheaper mouse. Thank you. m(_ _)m