This is a 10" bonsai drip / humidity tray. The big one on the bottom. The 4 sizes were shown for comparison. These are used to catch water that can drip through the pot onto a table top, etc.. They are also used to humidify a bonsai by the holding fine gavel and the water. The overall dimensions of the 4 sizes starting with the largest is: 1 1/4 x 7 1/4 x 10 1/2, 1 1/4 x 6 x 8 5/8, 1 1/4 x 4 3/4 x 7 and 7/8 x 3 7/8 x 5 3/4. Prices will list for 10", 8", 6", 4". these do not necessarily correspond with pot sizes and I would suggest always buying the next size up when in doubt.