Dial / card diameter

• SR4 commonly uses ~175 mm card; Tengfei offers 165 mm and 180 mm variants. A 165mm dial is smaller and 180mm slightly larger than a 175mm SR4 — that can affect readout and binnacle fit. Measure the installed card diameter in the SR4. Outer dimensions & mounting holes

• Confirm outer diameter, mounting-hole pitch and axis size (Tengfei lists outer dims and axis sizes for 165/180 bowls). If hole pattern/axis differ you’ll need an adaptor plate or new binnacle cut.

Type approval / standards

• Ensure the replacement is type-approved to the same authorities/standards required for the vessel (SOLAS / IMO / ISO / classification society). Tengfei advertises ISO/IMO compliance for CGF models — verify current certificates for the serial number you’ll receiveMounting orientation (projection vs vertical)

• SR4 is a Class A compass designed for binnacle mounting; choose the correct CGF model (projection/reflector/vertical) to match how the SR4 was used (overhead projection, binnacle, repeater, etc.). Illumination & electrical

• Check lamp/illumination voltage (AC220V / DC24V are common on projection types) and whether any repeater/TMC sensor connections are needed. Confirm wiring and feed in the existing binnacle. 12