The EPS-51CS SD is a replacement needle that performs identical to the original needle, not the manufacturer made needles for use with National record cartridges. This replacement needle is a "synthetic diamond needle" type. This is a generic model that plays a regular range of sound ranges, with a standard conical shape. General life is about 200 hours. The successor to the N.36-P51 EPS-51CS RED (4951586256304).