Professional Veterinary Calving Instrument – Tools Masters UK. Heavy Duty Calving Aid – Stainless Steel. 66 Total Length? Precision Ratchet Control? 3 Hook Attachments? Stainless Steel? Large Breed Cows. A Complete 66 Calving Aid Built for Large Breed Cows. You get a professional 66 ratchet-style calf puller specifically designed for large breed cows – with …