E-Z Fin™ (Finserts) Threaded Inserts for Plastic

E-Z Fin™ (Finserts) are a quick solution for adding machine threads to plastic materials. Each Finsert is designed with one, two or three OD fins that distribute stress over a greater surface area to minimize the possibility of cracking and protect against thread erosion. These brass threaded inserts for plastic are available with internal thread sizes ranging from #6 to 5/16.

Important Note: Hole size requirements may vary depending on a number of factors, including material and tools. We recommend that you test your particular application before ordering any E-Z Fin™ thread inserts for plastic. Samples may be provided to distributors upon request!


  • Easy press-in installation
  • Design minimizes splintering and splitting
  • Available in 3 lengths for varying material thicknesses

E-Z LOK™ has additional brass inserts for other applications, including soft wood and thermoplastics:

View All Available Brass Inserts

Benefits of Using Brass Threaded Inserts for Plastic From E-Z LOK

E-Z LOK's selection of threaded inserts for plastic is here to help you add machine threads to plastic materials and get the job done right every time. Durable and reliable, our Finsert line of thread inserts for plastic offers a variety of benefits. When you use any of these brass threaded inserts for plastic, you can expect the following perks:

  • One, two or three fins. Designed to distribute stress over a greater surface area, the fins will minimize the chance of cracking and protect against thread erosion.
  • Variety of internal threat sizes. With options ranging from #6 to 5/16, you're sure to get the exact type of thread inserts for plastic you require.
  • User-friendly installation. With easy press-in installation, our thread inserts for plastic make the application process quick, simple and hassle-free.

1. When Installing Threaded Inserts for Plastic, What Is the Recommended Wall Thickness for the Boss?

When you install threaded inserts for plastic, the overall boss thickness required depends on the material being used and the mold configuration creating the hole. The rule of thumb is to go with twice the thickness of the part diameter. However, the diameter should be increased if there is a potential for knit lines along the boss due to mold configuration.

2. What are Threaded Inserts Used for?

Threaded inserts are used for many types of applications. They're most commonly installed in plastic casings, housing and parts to create a metal thread.

3. If I wish to speak with an E-Z LOK team member about your thread inserts for plastic, how can I contact them?

Our team members are more than happy to assist you with any questions or concerns that may arise. You can email E-Z LOK at sales@ezlok.com or reach out using the following phone numbers:

  • Toll-Free: 800-234-5613
  • Local: 310-323-5613
  • Fax: 310-353-4444
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