Brexit: Coffee cup confusion - the Internal Market Bill explained
A row is - ahem - threatening to boil over about what can and cannot be sold in Wales in future.
That's because of controversial laws designed to keep trade flowing freely around the UK after Brexit.
The UK Internal Market Bill is meant to help businesses sell their goods in all parts of the country.
The Welsh Government calls it a "power grab" and a committee of Welsh Parliament members has said it "appears to be an attempt to recentralise control to Westminster" - but UK government ministers insist they are devolving more power to Cardiff post-Brexit.
Scrutiny of the bill resumes in the House of Lords this week.
A humble coffee cup - and the BBC's political correspondent Daniel Davies - are on hand to take us through the issue.
Produced and edited by Nick Hartley.