which ng/ml urine test to buy?

[essexboy]

I want to get some home urine testers. Which level should I buy. Is a 50ng/ml tester looking for a high or low level in your system. Most I've seen online are 15ng/ml. Is 15 too high a test for most jobs?
Many thanks

[rockbuds]

here in the US most tests have a 50ng cut-off

[kermitthehermit]

The lower the threshold the safer you can feel.
If you pass 15ng, 50 is a breeze.