These pots are 3 1/2" opening and 3" tall. Great for medium sized plants such as Venus flytraps, younger Sarracenia etc. They are dark green in color with a smooth finish to keep your media from sticking inside during transplanting. The walls are thick, almost crush-proof with drainage holes in the bottom. A rim around the top adds to the strength and ease of handling. We've been using the same pots for years, and have only broken after many years of use and being stepped on. Just wash, and reuse!