328 fuel accumulator vent hose size

Can someone verify the size hose that comes out the back end of the accumulator and runs up to the left tank? I had seen 5/16" mentioned in several threads here, but I got a new accumulator (Bosch 0 438 170 004) and the nipple is too small for 5/16" hose. The accumulator nipple has a 0.24" barrel and 0.275" rib so I assume it's probably for 1/4" hose (and I assume the tank nipple would match, but don't know).

 

Oh man, that is golden info, thanks!