APM Hexseal invented and patented pre-assembled self-sealing fasteners designed to provide both fastening and sealing integrity in a single unit. Our design features a resilient O-ring held captive in a precision engineered groove under the fastener head. This combination of precise groove geometry and O-ring characteristics results in an absolute seal regardless of surface finish, while still providing full metal-to-metal contact. Vibration-resistant and re-usable, SEELSKREWS, SEELBOLTS, and SEELRIVETS can withstand internal/external pressures up to 20,000 psig/vacuum at temperatures from -160 degrees F to +500 degrees F (-106 degrees C to +260 degrees C).* Made in the U.S.A., APM self-sealing & self-locking fasteners are available in standard and metric sizes in a wide choice of head and fastening types including self-tapping, and tamper-resistant. Typically, they are furnished in stainless steel/with different finishes or colors as may be required. All have pre mounted silicone rubber O-rings. Other elastomeric materials are also available to match and handle exposure to various chemicals and solvents (see materials table 1 on page 5). Consult factory for further information and pricing. They represent a superior sealing alternative to sealing compounds, tape, chemical coatings, and deformable washers that attempt to seal the threadform.