This is part of a product line from Elesa & Ganter, a leading manufacturer of innovative, standardized industrial components. The numeric sequence is associated with a particular product design; in this case, it refers to a bi-material manual indexing plunger. The first digit (1) indicates the bi-material elements which make up the body of the plunger, which is composed of a black, thermoplastic body and a stainless steel knob. The second set of two digits (50) indicates the plunger's diameter, which is 50mm. The third set of two digits (30) represent the plunger's length in millimeters, which is 30 mm. The fourth letter (M10) represents the thread size and type, which is M10 metric. The fifth and sixth digits (28 & 70) indicate the plunger's pre- and post-travel lengths, which are 28mm and 70mm respectively.