The turbo SPD prefilter is used to protect the turbo core from foreign objects such as metal particles or other unwanted media. Kit with three replaceable filter inserts included. 30 micron 80 micron 150 micron 30 micron filter the smallest particles and 150 micron filter the biggest. If your engine fails the turbo often fails with it because of metal parts is transported with the engine oil into the turbocharger core. With SPD's turbo pre filter, you do not risk damaging the turbo. SPD prefilter is installed in line with the turbo oil inlet hose.. The oil filter can be disassembled, cleaned and checked for metal parts at service and give a good indication if something is wrong. Connections: AN3 All SPD products hold the absolute highest quality and are carefully tested to work in the most demanding motorsport.