100-1000L/H Rotameter Plastic Tube Type Water Liquid Flow Meter LZS-15 for DN15 1/2" Tube

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.

Perfecto

I used this product for a flow indication in a non pressurized solar water heating system. It arrived and I discovered that it has some strange, incompatible female pipe thread that does not match anything that is domestically common. I was able to tap the plastic for 1/2" NPT , while being careful not to crack the cheap plastic housing. While in use, it did develop a leak and I will be replacing it with a higher quality, US standard compatible unit shortly.