I’m very happy with my Bison. I’ve bought this to house a battery to power my home office set up via a 300w pure sine wave inverter should we start loosing power over the winter. I took a punt and after spending some time measure the Bison myself I ordered a battery that is larger than the maximum recommended size, a Numax CXV35MF 120Ah Deep Cycle Battery and it fits a dream with no modification except to pull the battery cables back through their holes in the lid and directly through the large battery terminal recesses. Love the large side handles on the Bison as they make carrying this 30Kg set up a breeze.