From that site:

Delsym 12-hour Cough Relief




15 mgs of DXM Polystirex per teaspoon (equal to 30 mgs of DXM HBr)
88.5 of DXM Polystirex per teaspoon (equal to 177 mgs of DXM HBr)

Delsym 12-hour Cough Relief is an extended release syrup. This means that the DXM isn't absorbed right away, rather it breaks down in the stomach under time. The DXM is coated with a special edible plastic called "polystirex". Because of the extended release of the DXM, it tends to build up in the system, which can be harmful in large doses. Most would recommend that one doesn't do this syrup recreationally, and I agree. It doubles one's chances for Olney's Lesions and is 2 times harder on your body than regular DXM. Delsym Cough comes in 3 ounce bottles. Each bottle contains 265.5 milligrams of DXM Polystirex (equal to 531 milligrams of DXM HBr).