From the website:
The Thanatar’s frame, built to accommodate the huge weapon and the power systems and fuel reserves required to supply it, is considerably larger than even the hulking Castellax. Its frame is also heavily reinforced, both to withstand the stresses of firing its principal weapon and protect it from incoming attacks. This factor, alongside the use of an atomantic shielding array, make Thanatars notoriously durable. Such is their resilience that Thanatars are beyond the ability of most small arms, no matter how advanced, to harm.
The Thanatar Seige-automata is a complete multi-part resin kit, designed by Will Hayes. This model is available to pre-order now and will be despatched from Monday 30th June.