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E-Z LOK™ Threaded Insert for Metal - Automotive - Carbon Steel - M12-1.25 (3/4" Reach) x 5/8-18

SKU: 329-1212

E-Z LOK™ Threaded Insert for Metal - Automotive - Carbon Steel - M12-1.25 (3/4" Reach) x 5/8-18

E-Z LOK™ (Solid Wall) Automotive threaded inserts are designed for use in spark plug repair. Internal thread sizes from M10 to M18 are available in a variety of lengths. In addition VW Case Savers are offered in through hole and blind designs.

All E-Z LOK™ (Solid Wall) Automotive inserts are installed using standard tools. No special taps or installation tools needed.


  • Spark plug sizes from M10 to M23
  • VW Case Savers in through hole and blind designs
  • Solid wall construction for greater strength
  • Install with standard tools…no special drill or tap needed
  • Preapplied adhesive on the external threads activates upon installation
  • Self locking – inserts won’t back out


  • Soft metals: aluminum, cast iron, magnesium, etc.


Unlike E-Z Coil™ inserts, which require a special tap and installation tool, E-Z LOK™ (Solid Wall) threaded inserts for metal are installed using standard tools, and installation is as easy as 1-2-3.

  • Simply drill the appropriately sized hole with a standard drill
  • Tap the hole with a standard tap
  • Turn in the E-Z LOK™ (Solid Wall) insert like an ordinary fastener with a screwdriver, bolt and jam nut, or an E-Z LOK™ drive tool.

E-Z LOK™ (Solid Wall) threaded inserts are self-locking and open immediately upon installation. The pre-applied LOCTITE™ on the external threads sets immediately allowing for the newly installed insert to be fastener ready.

E-Z LOK solid wall threaded inserts are typically installed with the slots up. The slots accommodate a screwdriver or E-Z LOK drive tool. When using a bolt and jam nuts for installation, the slotted end of the insert can be either up or down.

Important Note: Hole size requirements may vary depending on a number of factors, including material and tools. We recommend you test your particular application before ordering. Contact us for free samples.

View Installation Instructions


E-Z Lok P/N: 329-1212
For Use in: Metal
Specific Material Use: N/A
Sub-Category: Automotive
Style: Solid Wall
Material: Steel - Carbon
System of Measurement: Metric
Internal Thread: M12-1.25
External Thread: N/A
Installed Length: 18
Drill Size: 37/64
Tap Size: 5/8-18
Minimum Full Thread Depth: N/A
Installation Tool P/N: N/A

Prop 65


WARNING: This product can expose you to lead, which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information, go to www.P65Warnings.ca.gov.