The MODX is a new unique concept of vivarium. It is supplied in 3ft sections, which connect together, allowing you to create as large a vivarium as you like. The main vivarium comes in a 3x3x3ft module, you can them extend to make the following you to make a 3ft, 6ft, 9ft, 12ft or an even larger vivarium. As well as being the perfect solution to creating a larger vivarium, it also has the added benefit of being able to extend as your reptile grows. A 'MAIN' module must always be purchased, and then you can add on as many 'EXTENSIONS' modules as you like. For example if you require a 3 x 3 x 3 ft - - You will need a Main vivarium For example if you require a 6 x 3 x 3 ft - - You will need a Main vivarium plus an extension vivarium