Have a look at Rapid Detect 6 parameter multi-drug test including both urine and oral method for instant and on-site for drugs of abuse identification. In this category, you'll find a range of products, including the Oralert 6 oral drug screen that can detect THC for up to 24 hours prior to testing. Another good saliva screen is the Oratect Saliva Drug Screen (AMP, MOP, PCP, COC, mAMP, & THC).
You can also find the traditional urine testing cups from such brands as Noble, iCup, and the E-Z Integrated Key Cup (CLIA Waived version available). There is also a couple version of the iScreen one step urine Test with different configurations that will check for the most common drugs.