The ND-15G SD is an alternative needle (replacement needle) that performs identical to the original needles produced by the manufacturer for Sony 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 SN.39-15 ND-15G RED (4951586410201).