Long-Lok® Strip Type

-320°F to +500°F
Reusability per IFI 124, IFI 524 and MIL-DTL-18240

The Long-Lok® strip fastener is a universally accepted, prevailing torque type self-locking fastener, with excellent vibration resistance. Over 35 years of use in thousands of proven applications attest to the wide acceptance of the Long-Lok strip. These fasteners are available in a wide range of sizes — from miniature eyeglass screws to fasteners for the heaviest of highway equipment.


Long-Lok strip fasteners are manufactured by forming a narrow longitudinal slot long enough to assure engagement with the female thread in an otherwise normal bolt or screw, and compressing a special locking material in the slot. The resiliency of the locking insert holds it in place without adhesives or thread distortion, allows it to recover slightly when disengaged, and provides vibration resistance on re-installation. This prevailing torque characteristic can provide re-usability performance in excess of 5 installation/removal cycles.

Several insert materials are available for operating temperatures ranging from -400°F to +500°F. Long-Lok also offers a specially designed stainless steel, rolled-tube insert for temperature requirements in excess of 1200°F.

Military Specifications:
MIL-DTL-18240, QPL-18240

Military Standards:
MS15981, MS16995-16998, MS18063-18068, MS18153, MS18154, MS21090-21099, MS21262, MS21295, MS51021, MS51023, MS51029, MS51031, MS51095, MS51096, MS90727, MS90728

Aerospace Standards:
NAS662, NAS1081, NAS1161-1168, NAS1171-1178, NAS1181-1188, NAS1189, NAS1190, NAS1191, NAS1223-1235, NAS1283, NAS1351, NAS1352, NAS1635 NAS4104-4116, NAS4204-4216, NAS4304- 4316, NAS4400-4416, NAS4500-4516, NAS4600-4616, NAS5000-5006, NAS5100-5106, NAS5200-5206, NAS5300-5306, NAS5400-5406, NAS5500-5506, NAS5600-5606, NAS5700-5706, NAS5800-5806, NAS6203-6220, NAS6303-6320, NAS6403-6420, NAS6500-6506, NAS6603-6620, NAS6704-6720, NAS6804-6820, NAS6900-6906

Commercial Standard:
IFI 124, IFI 524 (Metric)

MaterialsColor CodeOperating Temperature RangeMaterial Specification
Polycap NylonGreen-60°F to +250°F; -51°C to +121°CASTM-D-4066
PCTFE (Kel-F®*)Blue-320°F to +390°F; -196°C to + 199°CAMS 3650
Vespel®Brown-450°F to +500°F; -268°C to + 260°Cn/a
Hot-Lok™*(Stainless Steel Tube)Silver-400°F to +1200°F; -240°C to + 649°Cn/a
Thread Size#0#1#2#3#4#6#8#101/4
"L" Insert Length.
Thread Size5/163/87/161/29/165/83/47/81
"L" Insert Length.420.480.530.562.562.625.750.750.750


Long-Lok is part of Novaria Group, a cohesive family of precision component companies, that consistently delivers optimum performance and sustainable growth within the aerospace and defense marketplace.
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