3M™ Dual Lock™ Reclosable Fastener SJ3749G, Pop-in Piece Part, StemDensity 400, Black, 26 mm x 26 mm, 5000 Piece/Case

3M™ Dual Lock™ Reclosable Fastener SJ3749G is a black, polypropylene reclosable fastener with a pop-in pine tree base and a square top. It has a stem density of 400 stems per square inch. The pop-in parts attach without the use of pressure sensitive adhesive and come with a variety of bases that can be inserted into holes of precise dimension. Installing these fasteners is easy and does not require any special equipment or skills.

This fastener is designed to overcome the alignment and installation problems often encountered with screws and hidden fasteners. It offers simple installation without the need for special tools. 3M™ Dual Lock™ Reclosable Fasteners are blind fasteners that are specifically designed for attaching automotive trim components. They feature mushroom-shaped polyolefin stems that snap together, forming a high tensile closure. These fasteners are primarily used to secure rigid and semi-rigid surfaces such as trim or door panels, instrument panel bezels, headliners, and other automotive interior and exterior trim.

How It Works
This pop-in fastener is designed to be inserted into a slot of a specific dimension where attachment is desired. Its polypropylene pine tree base grips the inside of the hole securely. The fastener can then be mated and engaged to a second Dual Lock fastener attached to a piece of trim or another part to firmly secure the parts together.

When two pieces of 3M™ Dual Lock™ Reclosable Fasteners are pressed together, the stems flex and the mushroom heads slide past each other. After passing the opposing mating piece, the stems snap back into their original position, and the opposing mushroom heads interlock. These fasteners provide high tensile strength but can be easily opened by cleaving or peeling open the closure.

Alignment and re-alignment are effortless, and no special tools are required for installation. This means that these fasteners can be used to attach components before they enter the final assembly plant, reducing the number of parts and assembly time.

Stem Densities
Combinations of stem densities and the engaged area provide adjustable and proportional engagement and disengagement force to meet application needs. Dual Lock fasteners are offered in three different densities (stems per square inch): 170, 250, and 400. Dual Lock fastener SJ3749G has 400 stems per square inch, offering the tightest hold, and can be mated to Type 170 or 250. It should not be mated with another Type 400 fastener because the hold would be so tight that detachment would likely result in damage to the parts.

Applications
3M™ Dual Lock™ Reclosable Fasteners can replace conventional mechanical fasteners in a wide range of assembly and attachment applications where reclosability or serviceability is desired. These fasteners are primarily used to secure rigid and semi-rigid surfaces such as trim or door panels, instrument panel bezels, headliners, and other automotive interior and exterior trim. Some examples of applications include:

• Vehicle headliners
• Attaching accessories and equipment
• Attaching window and door trim panels
• Vibration and sound damping control
• CHMSL cover plates
• Center console flanges
• Interior trim
• Sunroof rings