Narrow frame doors require precise locking systems that balance strength, compliance, and installation flexibility. The Narrow Stile Mortise Lock DDML023 is engineered for slim-profile door applications where space is limited but performance standards remain uncompromised. With a compact case structure and multiple backset options ranging from 20 mm to 35 mm, this lock integrates smoothly into aluminum profiles, steel doors, and wooden narrow stile systems commonly used in commercial and architectural projects. Tested to EN12209 Grade 3 with 200,000 operational cycles and certified to EN1634 with a 240-minute fire rating, it meets strict European compliance requirements for safety-critical installations. Its narrow design combined with robust internal mechanics makes it suitable for both interior and exterior swing doors where durability, fire safety, and standardized configuration are essential.