The second Estonian kroon currency was introduced in 1992, after Estonia gained independence from the USSR. The kroon was subdivided into 100 cents (senti; singular sent). The fifty senti coin was a small circulating denomination.
The coins were made of Aluminium-bronze, with composition of 93% copper, 5% aluminium and 2% nickel.
Coins issued in 2006 circulated for only five years until 15 January 2011 when they were demonetised and replaced with the Euro, when Estonia joined the Euro currency.
The obverse depicts the three lions passant gardant (walking to left, facing the observer) of the Coat of Arms of Estonia. The date 2006 is divided by the lions.
There is a tiny inverted letter M above the right (upper) front paw of the lower lion.
At centre, the numeral value 50, below that the denomination SENTI. Around above, · EESTI VABARIIK · (Republic of Estonia).
There is controversy about the tiny letter M on the obverse. It is not a mint mark; it was originally present on coins minted by Juveel, but Juveel never had a mint mark for coins (it has markings on its other production); also, the letter is present on coins made later at other mints - such as this one. The general opinion seems to be that the letter M is a privy mark of Rein Mikli, who was director of Juveel at the time the original dies were made.