Heavy-duty cylindrical knobsets; designed for use in high traffic areas such as office building, schools, churches, restaurants, retail stores and warehouses; complies with ANSI A156.2, Series 4000, Grade 2 (400,000) cycles, UL listed for 3 hour fire door. Door range: 1-3/8" to 1-3/4". Backset: 2-3/4" standard. Commercial and Residential. Indoor and Outdoor. Fits standard 161 door prep, Schlage C keyway, keyed different; includes 2 nickel silver keys.