When I first looked at it this morning for some inexplicable reason I thought that I was looking at very dirty glass, still bleary-eyed ... but it's a stonewear flagon, and the 20 probably refers to litres? The bad news is that you will need to get a better image of that top line, which is most probably the manufacturer/brewery .... It looks as if it may start with Eug. for Eugene? Then Los..But I just can't tell on my laptop. Not sure where you are from, but over here in the UK there were hundred, possibly thousands of tiny breweries who had their own flagons marked, and I imagine with their interest in the stuff there were again probably hunndreds or thousands.. The one in the picture is interesting as the name isn't just stencilled on, and its not been glazed,
Other than Ardennes and it coming from Belgium...?
Hopefully someone else may be able to help.