The largest breather we stock at 77mm across and 73mm tall, sized for engines producing more crankcase pressure than a small filter can vent. Big-capacity motors, high-boost turbo builds and dry sump systems all benefit from the generous element area, which keeps back pressure low so the crankcase can breathe freely rather than forcing oil past the rear main seal. It is the natural match for larger catch tanks and vented dry sump reservoirs where the vent port is already generously sized. Check bonnet and strut tower clearance before committing, as the taller body needs more room above the tank than the 40x40mm or 60x50mm options.