The (often identified as the dormakaba Commando ) is a heavy-duty hydraulic device designed for high-traffic commercial environments, including storefront glass doors and hollow metal steel doors.
Unlike cheap closers that use a mechanical arm latch, the 669G uses a . The manual shows you exactly how to engage the "backcheck valve" to create a temporary hold-open position at a specific angle (usually 90°). Push past that point, and the door releases. It’s elegant, silent, and requires no extra hardware. dorma door closer 669g manual