Their head is short and broad, their bridge is bowed and the snout may not be pointed. Mongolian gerbils have relative big and round eyes. The small ears are oval and covered with fur. For a summary with pictures you can visit The Gerbil Colour Palette. A good housing is a large glass tank with a solid wire lid.
Mongolian gerbils enjoy digging very much.
If you want that they can dig, you'll have to use sand as bedding in at least a part of the tank. You can also use wood-shavings as bedding. When you use just wood-shavings and no sand as bedding, you'll have to give them a sand bowl filled with bird sand mixed with chinchilla dust. Gerbils love to take a sand bath and this also helps keeping the fur nice and dry. You need also in each gerbil tank a place to sleep in.