The present invention relates to a synthetic library of humanised antigen specific binding molecules derived from a member of a species in the Elasmobranchii subclass, processes for the production thereof and specific antigen specific binding molecules isolated from said library. The present invention also relates to the multi-domain specific binding molecules comprising humanised Ig-like Novel Antigen Receptor variable domains (VNARs). Specific binding domains that bind to Tumour Necrosis Factor alpha (TNFα) are also provided.