This app is using to converting amounts from Slug to Stone as well as converting amounts from Stone to Slug.

First of all, let us talk about Slug type and Stone type:


Slug (sl):

The slug is a derived unit of mass in the weight-based system of measures, most notably within the British Imperial measurement system and in the United States customary measures system.
Systems of measure either define mass and derive force or define a base force and derive a mass unit.


Stone (st):

The stone is an English and imperial unit of mass now equal to 14 pounds (6.35029318 kg).
England and other Germanic-speaking countries of northern Europe formerly used various standardised "stones" for trade, with their values ranging from about 5 to 40 local pounds (roughly 3 to 15 kg) depending on the location and objects weighed.
The United Kingdom's imperial system adopted the wool stone of 14 pounds in 1835. With the advent of metrication, Europe's various "stones" were superseded by or adapted to the kilogram from the mid-19th century on.
The stone continues in customary use in Britain and Ireland used for measuring body weight, but was prohibited for commercial use in the UK by the Weights and Measures Act of 1985.



By the way, As far as I told, this app is useful for converting amounts from Stone to Slug and vise verse.
So let's start using that.