Review on Aliyaduo 8 Pack Fish Tank Divider Set - Snap-Together & Easy-Cut Plastic Aquarium Separator Panels - Grid Isolation Board, Egg Crate Fish Tank Bottom Tray by Morgan Davis

I only received 4 packs but the seller responded quickly and refunded 1/2 of what I paid to make up for it. They only connect in one direction, so you have to switch sides. It's not obvious so I can see how some people might try to combine them and break them. Look closely at the little cone in the joints to see how to put them in. They are ideal for standard 20 gallon, 29 gallon and 55 gallon aquariums with an internal width of approximately 12 inches. Two is just right for a 20g length, three is just right for 29 gallons and three works for 55 gallons but about 2 inches off the top, which you can do with a thick layer of gravel. You need to trim them to any other aquarium size. The holes are smaller than some of the other similar dividers so I chose them. Hopefully these spacers will allow me to have 2 pairs of clowns in a 55 gallon tank. Just take a look.