If you're driving a high-mileage Volvo (perhaps 150K+), and notice some buildup on the front of the oil pan behind/below your oil dipstick tube, definitely get this replacement. It's a nice, strong, thick gasket that goes on the end of the oil dipstick tube where it sits into the oil pan. Prevents some oil loss, too, needless to say. Be sure to apply some silicone grease during installation!

It was a good idea to replace the washer since when I pulled the dipstick there was all sorts of oil crud deposits I wound up cleaning out of the dipstick itself and the port on the engine block. Get that silicone lube on it and press it hard back into the block and you're good to go once you screw back on the bolt. Clean everything up and watch the area for oil leaks. Several hundred miles on mine so far so good. The washer is a very distinct color too so it makes spotting it very easy.