[MENTION=205284]rekmeyata[/MENTION] You can see the cable release thumb buttons hanging down like beagle ears in this photo of the 3400 shifters, below and behind the cable output. (photo from Chain Reaction). These don't have the release lever behind the brake lever like the 3500. What you see as a button on the 3500 shifter, is actually the output for the shifter cable, which on the 3500 also has a barrel adjuster, making it look big. The new Sora R3000 has aero shifter cables and nothing hanging off.