Sinn refers to this as their "Technical-Sporty Chronograph" model, and it features a square "television" case and chronograph registers, angular markers, and modern styling. A limited edition of 150 pieces, Ref. 901 was introduced in 2012 but it recalled the similar Audi Design chronograph, Ref. 9901.010, produced in 2004. The square case is also related to the Ref. 9901.020 Audi Design watch as well as the limited-edition Sinn Ref. 902.
The Ref. 901 chronograph uses a Valjoux 7750 movement, with 30-minute and 12-hour chronograph registers at 12:00 and 6:00, respectively, and small seconds at 9:00. A date window is located at 3:00. The trapezoid hands are different from the Audi Design model, as are the "M"-shaped markers at the corners. Large rectangular pushers frame the modern crown, while a novel strap adjustment lever is located on the opposite side.