PN#600173-6  SKU#12887  4-1/4″ Locking Diesel Fuel Cap. Male, Non-Vented, Locking. Nominal Size: 4 1/4″ Inches. Finish: Aluminum. Threads: 8 Per Inch. Across Threads (Cap): 4-1/4″. Fusible meltouts for thermal relief. Safety chain and crossbar included. Patented Loc-Gard protects against moisture and contaminants. Designed for use only on vehicles equipped with properly vented fuel systems.