This is a 18.5ci Wizard block.  That makes it a little larger than a KG4 and a little smaller than a KG7 which makes it an excellent choice block for a KG4 KG7 motor.  It is excellent STD bore and comes with 2 used pistons and 6 NEW Mercury rings.  I had to put 3 heli-coils in the rear block cover bolts and they are done right.  The 2 pistons are from this block.  Excellent used condition.