Purpose and key benefit High-quality M16 x 1.5 pipe fasteners designed to reliably seal openings in machines, fittings and pipework. They stop leaks, prevent contamination and close unused ports so systems run cleanly and safely. What’s included 2 pieces per package Thread diameter: M16 x 1.5 mm Internal hex width: 8 mm (0.31 in) — fits a standard 8 mm hex key Overall size (D x H): 22 x 17 mm (0.87 x 0.67 in) Material and performance Made from 45# steel for strength and long service life Supplied with sealing rings for precise sealing and reliable leak protection Corrosion-resistant construction suitable for demanding environments and repeated use Design advantages Internal hex head gives improved leverage and precise control with a hex key for secure, accurate tightening and removal Compact dimensions work well in confined spaces and on fittings where external wrench clearance is limited Typical applications Automotive: seal intake manifold ports, pump connections or engine jack holes during assembly, maintenance or testing Industrial and marine: close test or service ports on exhaust manifolds, ship pipe systems and industrial piping Pool and plumbing: cap the ends of swimming pool pipes or other plumbing lines during repairs or winterization Why choose these fasteners Simple, effective sealing solution that reduces downtime and prevents fluid or gas loss Robust steel construction and sealing rings deliver dependable performance in automotive, marine and industrial settings Easy to install and remove with a standard 8 mm hex key, making maintenance faster and more precise Compatibility note: thread specification is M16 x 1.5 mm; confirm matching thread size before installation.