Design and Build
The BenQ-Siemens C81 features compact dimensions of 104 x 46.5 x 17.7 mm, making it a comfortable fit for the user's hand and pocket, typical of the mid-2000s candy-bar design. Weighing just 90 grams, the phone is lightweight by modern standards which contributes to its portability. The C81 uses a Mini-SIM card, a common choice during its time. Its black body, which was marketed as Piano Black, gives the device a stylish yet classic look, although it lacks the modern sleekness found in contemporary devices.