K & M 18853 Adaptor for Spider Pro – Black The reinforcement for all Spider Pro and Baby Spider Pro models. The metal mounting plate is simply mounted under the plastic lid. Threaded bolt with 3/8" connection increases the extra potential of the Spider Pro. So even the heaviest oscillating arms and music stands with extension can be securely and stable. Version: black. Material: steel. Features: reinforcement for mounting heavy swivel arms and music stands. Dimensions: 136 x 85 x 29 mm. Weight: 0.125 kg.