This miniature achromatic telescope has a rayskin-covered barrel and a single draw tube. Unusually for these relatively simple telescopes, it has a choice of two eyepiece lenses of different magnifications. A slide in the eyepiece allows one or other to be selected. Two engraved lines on the draw tube indicate the optimum working length for each of the lenses.

Though well made, this was a fashionable accessory rather than a serious telescope. Although the main trade of an instrument maker like Ramsden was in navigational instruments, like sextants, the manufacture of small expensive items like this spy glass provided extra income. Ramsden's name is engraved on the eyepiece and the original leather case still survives.