Sinclair Wrist Calculator.
Display is 8 digits, red LED.
4-functions, %, memory, square root.
8.1v (6x mercury cells).
Integrated circuit - Mostek MK50321N, here date coded mid-1976.
47 x 45 x 18 mm (1.9 x 1.75 x 0.7 ins).
Made in England by Sinclair Instruments Ltd.
