This 4000 series tank o-ring is an OEM product, not a generic one, from PENTAIR WATER POOL AND SPA INC. It is compatible with in-ground pools and is a modern style pool accessory made in China. The model number for this unit is 071439 and it comes in a single unit quantity. This product does not come with a custom bundle and has not been modified. Additionally, it is important to note that this product carries California's prop 65 warning.