For Gen2 3SGTE valve cover PCV vent line removal/replacement, use the 5/8" clamp on.

For Gen3 3SGTE valve cover Catch can removal/replacement, the measurement is about 7/8", so you can press the 3/4" unit over it with a little effor (no clamp required) or try to clamp down the 1" unit.

NOTE: Be sure to use the K&N purple oil *extremely* sparingly because the amount included is enough for about 10 breather filters -- KO Racing always applies this with a drop or two per pleat in the breather filter.