The Berliner Percussion Hammer is a neurological diagnostic tool featuring a heavy, circular rubber head attached at a right angle to a stainless steel handle, typically 20cm long . Developed by Bernhard Berliner in 1910, its larger striking surface and weighted head provide a firm, accurate percussion for testing deep tendon reflexes like the knee, bicep, tricep, and Achilles . It is a reusable, autoclavable instrument widely used in clinical and veterinary examinations .