IMS Pavoni Lever Precision Double Filter Basket ø 49mm - B582TH22 From  £21.24

High quality item. You can see and taste the difference from other filter baskets.
I wish it was 2mm deeper.

So I recently purchased a budget espresso machine (John Lewis & Partners Pump Espresso Machine), which comes with a pressurised filter basket. Since then I have been searching for a compatible unpressurised basket.
This is the first one I found that sort of works.

It sits a bit loose in the portafilter, but it does form a tight seal to the group head.
The only issue is that the lip is curved (the original supplied filter basket has a flat lip), so you can't fully lock the portafilter in place. It still works for making delicious coffee as long as you hold the portafilter in place during the brewing process. Am thinking about filing the lip down... Either way this is a massive step up over the filter basket that came with the machine :)

Highly recommend

We did pickup some couple of this double filter baskets to make multiple back to back shots and we were never been happier to enjoy our coffee!

Huge improvement on rhe quality of extraction on my europicola

Pro: Hole size is clearly much more consistent vs. normal filters. In my experience this seems to improve consistency and reduce channeling.

Cons: A bit shallow, 2-3 mm more would be better. A tad bit too wide too. I use a 49,5mm tamper and it feels like I could use a 50mm tamper