Small Indexing Plunger with Circle Plastic Clamping Knob, rest position, M8 x 1.0 x 15mm, D21, pin4
PSK300F-2108150406
Spring loaded pull pin, Indexing plunger, Pop pin
A short-stroke plunger with a convenient dwell notch for mid-operation stops. Without a stay-pulled feature, users must hold mini plungers continuously. Our improved design covers M8–M16, 4–10mm pins, with a ringed knob plus four styles, seven ring/disc color options, and a “stay-pulled” solution: pull, rotate, and it stays open. Taiwan CNC and mold processes deliver high precision and durability, while wood fiber or oyster shell plastic aids sustainability. ISO9001 oversight lets UJEN serve large or custom B2B orders in medical, sports, automotive-aerospace, semiconductors, and beyond.
Function
UJEN Mini Spring Pull Pins with Rest Position are designed specifically for rapid fastening, frequent adjustment, and convenient repositioning. Simply pull and rotate the top knob 36 degrees to maintain the pin in a fully disengaged (rest) position, allowing users the freedom to adjust components easily with both hands.
After repositioning, simply rotate the knob directly to re-engage the pin into the hole (new improved feature), eliminating the need for an additional pulling action. This innovative improvement significantly enhances operational efficiency.
Additionally, this mini pull pin enables quick hand-tightening by rotating the top knob manually, securely fastening components and effectively preventing vibration or looseness without tools. Widely used in fitness equipment, medical devices, mechanical assemblies, furniture hardware, and more, it provides a reliable solution for precise and rapid component adjustments.
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)
- 15 / 0.59
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, rest position, M8 x 1.0 x 15mm, 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, rest position, M8 x 1.0 x 15mm, 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.