OTS circuit for 4-20mA output

I have spent days searching forums, aliexpress, ebay, and more, looking for an off the shelf product that will take a power supply and PWM signal and give out 4-20mA, trying to avoid adding lots of resistors, capacitors, chips and transistors to my design.

I have found this, has anyone ever used one/anyone got any comments:

The reason for wanting this is to measure volume of liquid based on a pressure reading (from a 4-20mA signal and 250 Ohm resistor), calculate volume as a percentage based on programmable dimensions, and then output 4-20mA based on overall volume as a percentage of maximum, I have everything working in the software, and all the hardware apart from being able to get my 4-20mA out - the 4-20mA output is different to the input, input is 20mA at fsd of the sensor, output is 20mA at 100% capacity, which could be as little as 30-40% of the sensor fsd.

I understand there may be cheaper ways to do this, but I am looking for simplicity and something ots, and if making these repeatedly the extra money may well be saved in labour costs!

Any comments on experience with the device or a similar one available would be appreciated!

Regards, Shaun