Master Cylinder: Aluminium 1 inch Universal- 3/8" ports - both sidesThis is an a 3 8 ports thread holes both sides .. consideration for those with cramped engine bays.. where it may be easier to run the brake lines out either on the LH or RH sides.. as is some RHD converted cars with cramped engine bays. Comes with a "bullet" to allow for deep MC piston to booster pin use or short. Ultra Light Weight GM Universal 1" Bore; 3 8" Ports on Both Sides; GM Universal Corvette style Cast Iron 1" Bore Master Cylinder. 9 16" &