Agar is a seaweed product dried and made into flakes or a powder . Both forms are used as a thickener most commonly in Japan and other parts of Asia.
You can purchase agar powder in many well stocked grocery stores such as Whole Foods Markets or most any Asian grocery story. Agar may also be purchased online at Amazon.com
1/2 teaspoon agar powder = 1 tablespoon agar flakes
1 teaspoon agar powder = 2 tablespoons agar flakes
1/2 teaspoons agar powder = 3 tablespoons agar flakes
3 teaspoons agar powder (1 tablespoon powder) = 6 tablespoons agar flakes
2 1/2 tablespoons agar powder = 15 tablespoons agar flakes (1 cup minus 1 tablespoon)