Small Indexing Plunger with Circle Plastic Clamping Knob, M8 x 1.0 x 20mm, D21, pin4
PSK300-2108200406
Spring loaded pull pin, Indexing plunger, Pop pin
Perfect for lab instruments, this mini plunger keeps calibrations secure. For mini machinery using screws or knobs, precise locking and appealing design matter. Our compact plungers cover M8–M16, with 4–10mm pin specs. This knob includes a ring and four shape variations, plus 7 color discs/rings for customization. Taiwan CNC and mold manufacturing guarantee accurate tolerances and durability, with wood fiber or oyster shell plastic for eco aims. ISO9001-compliant, we handle high-volume or bespoke B2B orders in medical, automotive, sports, and semiconductor fields.
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
- M8 x 1.0
Thread Material
- Steel
Screw Length(mm/inch)
- 20 / 0.79
Plunger Diameter(mm)
- 4
Metal Finishing
- zinc plated with trivalent
External Diameter(mm)
- 21~24
External Height(mm)
- 21~24
External Material
- PA6+GF
External Shape
- Circle
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Small Indexing Plunger with Circle Plastic Clamping Knob, M8 x 1.0 x 20mm, D21, pin4 | 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 Plastic Clamping Knob, M8 x 1.0 x 20mm, D21, pin4, 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.