Brass with enamel dial.
Consists of a cylindrical body 1.7" (4.3cm) diameter; a tapered nose cone with a brass ring at its poited end to which a towing line can be secured, a stabilising fin secured to the body abaft the centre and a rotating section fitted with four fins.
Registering mechanism is set into the main body of the instrument and consists of three pointers which are driven through spur-gearing operated by a pinion on the end of the rotator shaft. Distance is indicated by the three pointers on an enamel plate: graduated every 10 miles from 0-100; every mile from 1-10; every 1/4 mile from 1/4 -1.