Product Description: All metal construction and aluminum process, for long time use High quality anodized aluminum adapter M42x1mm male thread to M42x0.75mm female thread adapter. Converts an M42x1mm female thread to a M42x0.75mm female thread. OR Converts an M42x0.75mm male thread to a M42x1mm male thread. External Threads: : M42x1mm Male External Thread Depth: 3mm/ 0.12in Internal Threads: M42x0.75mm Female Internal Thread Depth: 4mm/ 0.16in Flange distance: 5mm/ 0.19in Total length: 8mm/ 0.31in Inner diameter: 39mm/ 1.53in The inner side of M42x1mm is fully irregular extinction threads Material: Metal colour: Black Package Contents: 1 x telescope accessories adapter ring Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.