Small Indexing Plunger with Circle Clamping Knob, M16 x 21mm, D33, pin8
PSK300-331621N0810
Mini spring loaded pull pin, Tiny indexing plunger, Pop pin
Ideal for short travel distances where speed and reliability are critical. If a compact structure still requires efficient plunger locking, Our selection spans M8, M10, M12, M16 plus 4–10mm pins. The knob includes a ring plus four styles, along with 7 ring/disc color options, and wood fiber or oyster shell plastic for reduced waste. Taiwan CNC and mold methods maintain tight tolerances and longevity, while ISO9001 compliance meets large or custom B2B orders. Perfect for medical gear, automotive-aerospace, sports equipment, semiconductors, and AV solutions seeking high-efficiency locking.
Function
UJEN Mini Spring Pull Pins are ideal for applications requiring compact size, frequent adjustment, and quick fastening. Simply pull the compact knob upward to release the pin from its hole, adjust the component to your desired position, and release—the internal spring immediately re-engages the pin for precise positioning.
Additionally, this pull pin features a special knob design allowing manual rotation to tighten screws directly by hand, ensuring stable clamping and preventing component vibration or loosening without needing tools. Perfectly suited for fitness equipment, medical devices, mechanical assemblies, and furniture hardware.
Features
- RoHS REACH compliant.
- Pull and release process smoother.
- Thread is class 2.
- Flame-proof, heat-resistant, anti-UV properties.
- The head knob has a matte finish.
- The head knob does not hurt hands, no sharp angles or burrs.
- The knob is easy to tight with a hand. the best design of beauty and grip.
- The metal is shiny and detailed.
- Zinc plated metal, stable corrosion resistance.
- The fitting tolerance between metal parts is small, reducing sway.
- The rounded corner of the Plunger's front end increases smoothness of insertion.
- The chamfered front end of the screw makes assembly smoother and reduces wear on the mating end face.
Dimensions

Thread Size
- M16
Thread Material
- Steel
Screw Length(mm/inch)
- 21 / 0.82
Plunger Diameter(mm)
- 8
Metal Finishing
- zinc plated with trivalent
External Diameter(mm)
- 33~36
External Height(mm)
- 33~36
External Material
- PA6+GF
External Shape
- Circle
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Small Indexing Plunger with Circle Clamping Knob, M16 x 21mm, D33, pin8 | Achieve Ergonomic Efficiency with Adjustable Handles for Machinery
Based in Taiwan since 1994, UJEN DEVELOPMENT CO., LTD. expertise in manufacturing high-quality Small Indexing Plunger with Circle Clamping Knob, M16 x 21mm, D33, pin8, hand screws, knob screws, adjustable handles, grip knobs, and indexing plungers. Their commitment to customization and precision ensures each component, from hand screws to indexing plungers, meets rigorous standards. This dedication positions UJEN as a leader in supplying durable and reliable industrial components to global markets.
UJEN Development Co., Ltd. is a leading manufacturer of precision-engineered hand screws, knob screws, plastic knobs, adjustable handles, and indexing plungers for a variety of industrial needs. Our 45-year legacy, combined with ISO 9001:2015 certification, underscores our commitment to quality, innovation, and customer satisfaction. Specializing in custom solutions, we excel in professional moldmaking, enhancing equipment functionality across industries.
UJEN has been offering customers high-quality hand screws for industrial machinery since 1994, both with advanced technology and 47 years of experiences, UJEN ensures each customer's demands are met.