The oil cooler hoover bit (or doghouse oil cooler sealing frame) was primarily designed to ensure that cooling air goes through the oil cooler! If this is missing (and they often are), the cooling air can bypass the cooler and your VW's oil temperature will skyrocket!
The hoover bit is the most commonly omitted part when people rebuild their VW engines. This will fit all 1600cc engines upgraded with a wider type 4 oil cooler.
Made in the USA!