It is a urine test.

It tests for 5 drugs (including THC) with a 50ng cutoff.

w/NIT means the sample is also tested for nitrates, which are usually found
adulterants (stuff people use to fool the test).

Like Hindu said, if you stop smoking now, and drink extra water, you should be okay.

It might be worth buying a detox product at your healthfood store that has creatine in it and something to balance your urine's pH, as this will keep your results from looking like you were chugging water to pass.