Culligan OR-100 Water Filter Housing O-Ring (5 PK) Culligan OR-100 O-Ring for Big Blue Housing These are not Sent in Culligan packaging, to keep cost down they are repacked in 5 packs Culligan OR-100 O-Ring for Big Blue Housings. If you take the o-ring out of the package and uncoil it, you will see that it is actually 5.75 inches in diameter Huge SAVINGS!!