All the bleeder screws I've seen on the Benz's are 9mm. I prefer to use a box wrench as it allow free flow of the fluid. Only use a socket to break the bleeder loose.
Can be done without the hose/tubing. The tubing allows for capture of the expelled fluid and no mess on the ground.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.