This is a lovely looking a very functional Chronograph from Hamilton.  The black dial has 3 wonderful sub dials in a golden hue that have lovely patina.  It has the original crown and buckle and all original parts.

Characteristic traits of the Lemania 5100 movement give the 3 sub dials their purpose. A central minute-counter, A 24h indicator and a 12-hour counter sub-dial.  All work perfectly.  The Red Second hand sweeps around the dial with a cool arrow head hand that counts the minutes when you set the chronograph (I think the arrow head also looks like a jet plane)  

This watch and calibre was popular with the Military. It was also used in other brands like
Omega, Fortis, Sinn, Alain Silberstein, Paul Picot, Orfina Porsche Design and Tutima.   

Tutima insisted on the 5100 as it was the the only calibre that met their military requirements.

The 5100, due to its construction, is the only chronograph movement that can withstand large shocks without its chronograph seconds hand stopping. This is because its chronograph mechanism is driven directly unlike most other chronographs which use an intermediate wheel. The calibre easily withstands acceleration in excess of 7G without appreciable loss of accuracy. Its ruggedness is legendary; the calibre easily absorbs shocks and blows. The calibre also maintains its accuracy over long periods without servicing. Service intervals from four to seven years have shown to be sufficient.

This watch will give you years of pleasure, is easy to use, looks great and needs much less servicing than most chronographs as detailed above.  It also comes with a light brown strap that was with the watch originally.