Key benefits Simple, fast connection: flange design lets you join duct sections quickly without complex tools or custom cuts. Accurate fit for known models: made specifically to work with ventilation units 12038 and 12025, preventing fitment surprises. Stable, screwmounted seal: screwhole spacing and roundtube sizing give a consistent mounting pattern for secure installation. Versatile circular compatibility: designed to mate with a range of circular ventilation ducts around the specified diameter. What it does and why you need it Functions as a flange adapter that links rectangular and circular duct elements, making installations and repairs smoother and faster. Reduces installation time and the need for improvised adapters or repeated field modifications. Provides predictable dimensions so installers and DIYers can plan cuts, fasteners, and supports with confidence. Key specifications (exact) Fits rectangular duct: 12 x 12 cm (4.72 x 4.72 inches) — compatible with ventilation applications for models 12038 and 12025. Round tube diameter: 11 cm. Distance between small screw holes: 10.5 cm. Practical use scenarios Replacing or installing ventilation for a bathroom or utility room: connect a 12 x 12 cm duct outlet on a 12038 or 12025 fan to an 11 cm circular exhaust run. Retrofitting an existing system: convert a rectangular duct outlet to a circular duct path without fabricating a custom adapter. Routine maintenance or upgrades: swap out worn adapters or add a secure flange when extending ducting to external vents. Compatibility and performance tips Verify your device model (12038 or 12025) and confirm the duct crosssection is 12 x 12 cm before . Measure the receiving circular duct to ensure an 11 cm diameter match for a snug connection. Use the provided screwhole spacing (10.5 cm) to select appropriate fasteners and mounting patterns for a secure, leakminimizing installation.