I have two examples in my collection, one struck at Lyon (Atelier D), the other at Lille (Atelier W). The Lille raises some question for me as it shows some anomalies not seen on coins of this type: first, it displays a die break on reverse which, I think, was the reason for the weak strike which can be seen in places. The other anomaly is the irregular spacing of the date, specially the '9' which is wildly out of line with the rest of the digits in the date. It have observed neither of these anomalies on any of the Ecu de Six Livres from Lille listed on Acsearch. Wider internet searches have also revealed nothing. The coin otherwise conforms well to the nominal specification for the Ecu de Six Livres de la Convention which are: diameter of 38,5 mm, nominal weight of 29,23g. The edge of my piece reads, in high relief, 'Dieu Protege La France'. So there you have it: if anybody has some experience on these, strike characteristics, general appearance, etc regarding this issue, I would greatly appreciate it. Thanks!