Works "sometimes". If there is a gap (like between 2 doors) it works well. If you are preventing excess paint onto a ceiling from a shared edge along a wall for example, I found it didn't work too well. Worth a shot I say.

I used masking tape for out side windows. Painting and re putty. Masking tape got stuck hard to peel off. > Bought this ,Sceptical at first. It works like a dream. Small paint edge and long edge are a excellent idea.Tip, make sure you don't overload brush with paint although did it a few times and did not really matter. Great idea , perfect for sash windows. Easy to use and clean.

I live in an old 1960's house where the walls are a little wonky, the only way this works is if you dry-brush the paint on so it doesn't bleed through the gaps, even in places where the wall is perfectly straight, but even using dulux that would take many many coats. I just ended up using an angled brush because with this I either had to clean up where the pain settled along the skirting or I had to do like 3-4 coats with barely any paint. Ended up being way easier just using a brush and a steady hand!