Review on LZS-15 Plastic Tube Rotameter For DN15 1/2" Tube - Measures Water And Liquid Flow At 100-1000L/H by Andrew Grimes

I bought this specifically to make a pump curve for a water circulating pump, so I didn't want to spend a lot of money. It worked well for my intended application and quality seems pretty good. As the description clearly states, tube size is DN15 (a bit smaller than 1/2" pipe. Since I was not putting any pressure on this, I tapped the fittings for 1/2" NPT and screwed a pvc adapter into it. Worked fine for a benchtop application, but I wouldn't recommend putting much pressure on this arrangement. Some multi-purpose cement on the threads would probably ensure no leaks and help with pressure capability, but do so at your own risk.