Direct after-market replacement part number: AO-WH-STD-OR-2   

Dimensions- 3.44” x 9 Cm Diameter

For A.O. Smith whole house systems:  AO-WH-PRE,  AO-WH-PREV and under sink system AO-MF-B.

Comes in bulk packaging. You will receive 5 O-rings of replacement part number: AO-WH-STD-OR-2   

User must install according to manufacturer specifications, improper installation will result in leakage.