This is a swinging reaction and aerial coil made of ebonite and brass. The pins on the underneath are a standard 4-pin valve layout and the degree of coupling between the two coils is altered by moving the brass arm which in turn moves the uppermost coil (the reaction coil) on its pivot.

The (faded) box states there were 4 ranges available: 80-200 metres, 200-500 metres, 500-1500 metres and 1500-2800 metres.

The one in the photo covers the 1500-2800 metre range and was the most expensive at 12 shillings.