The 09251-F/45 is a filter assembly kit containing a retainer, a guard, and a 45 PPI filter media. It is designed to fit 60 mm (2.36 inch) square fans, with overall dimensions of 60.0 mm x 50.0 mm x 6.6 mm. The plastic guard and retainer components meet the UL94V-0 flammability standard, ensuring safety in electronic applications. The filter media itself complies with the UL94HF-1 standard, providing reliable filtration to protect internal components from dust and debris in various cooling systems.