Purex (P-24218/07-1439) SM/SMBW 4000 Series Lid O-Ring | O-333-BAGGED Pentair Quick Ship MasterTemp Pool and Spa Heaters (NATURAL GAS) It's able to do this

It's able to do this because the rollers are given the freedom to move up and down which conforms to the object

AquaStar 10" round star anti-vortex drain in black for Pentair In-Floor systems

Hayward AquaBug/Penguin/Wanda the Whale/Diver Dave/PoolVac Ultra/PoolVac XL/PoolVac V-Flex/PoolVac Classic/Navigator V-Flex/Navigator Pro/Hayward Blu Lower/Upper Body Screw - 6 Pack (AXV065P)

It also prevents air from leaking into the filtration system which can cause some issues with other parts of the equipment

Purex (P-24218/07-1439) SM/SMBW 4000 Series Lid O-Ring | O-333-BAGGED Pentair Quick Ship MasterTemp Pool and Spa Heaters (NATURAL GAS) It's able to do thisPurex (P 24218 07 1439) SM SMBW 4000 Series Lid O Ring O 333 BAGGED Replacement Lid O Ring