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 not a single one has fallen apart! Just wash, and reuse!