Product description What's the difference between standard model and heavy duty model? This heavy-duty coupler lock features a and thicker steel U-shaped pipe and a 100% solid, offering resistance to external forces and attempts. What sizes of couplers is the trailer coupler lock compatible with? It suits for 1-7/8'', 2'' and 2 5/16'' couplers. Are the for the two-pack keyed alike? Yes, the are keyed alike. From the brand Universal Fit & Adjustable Design - trailer coupler lock features 11 locking positions, compatible with 1-7/8", 2", and 2-5/16" couplers for a versatile fit across various couplers. Heavy-Duty Construction - With a and thicker steel U-shaped pipe and, this lock offers resistance to external forces and attempts. - Crafted from an and high-strength A36 steel, this trailer hitch lock provides robust cut and shear resistance. Rustproof, weatherproof, and QC product quality certified. Upgraded Lock Cylinder - For added strength, the tow ball coupler lock features a complex lock mechanism and thicker, making it virtually impossible to crack and increasing key durability. Satisfaction Guaranteed - a 120-day warranty and responsive 24/7 customer support. If you experience any issues, simply reach out via the "Ask a Question" button for assistance. We're committed to providing top-notch service.