The lower the micron rating, the finer the filtration. Follow your engine manufacturer's recommendation for fuel filter micron rating.
S = Secondary/Final 2 micron (Brown)
T = Primary or Secondary/Final 10 micron (Blue)
P = Primary 30 micron (Red) Color Blue Micron 10 Fits 345RC/445R/645R

Price is per unit.Also available in a case of 12. Please call us if interested in case pricing.