The 4" Quick Pitch Center Ring is NOT required when you are already using the 6" Universal Center Ring to accommodate a Ebbe square drain assembly.
The 4" Center Ring is a collar to protect cement from bonding to the drain threads allowing a tile setter the ability to adjust the drain height to the thickness of tile after the mortar bed is cured. This center ring is used with the Extra Quick Pitch Float Sticks and can be used with either a Round 3 Part Drain or a "low profile" square drain. If purchasing an Ebbe square drain assembly from this site, you will require the 6" Universal Center Ring. This ring is adaptable to any 3 part drain with a thread that exceeds 1.5" in height. Don't forget a Positive Weep Protector.
This 4" center ring is included in the Quick Pitch Standard Kit, use with a round drain grate type assembly.