Shimano 105 Shifter and Brake levers ST-5500 2 x 9 speed flight deck | eBay
Vintage Shimano 105 Shifter Left Front ST-5600 10 Speed STI 10s Flight Deck | eBay
Whats Shimano Flight Deck all about? There is a ribbon cable inside and what seems to be a button by the thumb of the shifter. What is it for? : r/bikewrench