Triple Scale Hydrometer.
This hydrometer is 230mm long and has three scales.
Specific Gravity 0.990 to 1.170 at 20 deg C, sugar scale 0 to 23 Balling (% sugar by weight), alcohol scale 0 to 23% for % alcohol calculation.
Instructions on how to calculate % alcohol are on an extension of scale.
The hydrometer comes packed in a strong clear plastic tube along with an instruction leaflet which includes a temperature correction table, and instructions on how to calculate actual % alcohol from the hydrometer readings.