Aluminum Locking Diesel Fuel Cap, 3.00 Inch Diameter (Part Number FC022-69) by Cleveland Tank. Heavy-duty locking fuel cap machined from lightweight, corrosion-resistant aluminum to resist leaks, cracks, and fuel contamination. Features a 3.00-inch nominal diameter with female threads at 8 threads per inch (8 TPI), a non-vented design, and a built-in locking mechanism to help deter fuel theft and tampering. Weighs 1.0 lb with overall dimensions of 3.0 x 3.0 x 2.0 inches. Designed as a direct-fit replacement diesel fuel tank cap for fuel systems requiring a 3.00-inch female-thread, 8 TPI fitting. Suited for fleet, vocational, and commercial truck fuel tank applications where a secure, weather-tight, anti-corrosion locking fuel cap is needed.