Stainless Steel 304 for corrosive environments, rigid and durable body design Precision CNC machined for tight, leak free performance and has polished finish appearance Clean metric M16*1.5 straight thread; Threaded though whole part; Suitable for common O2 automotive and motorcycle replacement sensors Use for your custom oxygen sensor install, exhaust, down pipe, headers, exchangers and other installations where weld-in or weld-on metric connection is needed Easy to weld; Stepped double sided design with thick top head flange Stainless steel 304 weld-on bung for installations in corrosive environments. Threaded for standard metric M16 x 1.5 parallel (straight). Thread goes all way though the part. Fits through 7/8" hole. Other sizes (e.g. Imperial NPT) and materials are available. Simple stepped design allows easy welding. Can be welded from either side depending on your requirements. See pictures and drawing for appearance and dimensions. Laser engraved on top face for easy identification. Let us know if you have any questions.