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When a repair calls for a spring so small it nearly disappears between your fingers, finding the right size is half the battle. Hobbyists, electronics technicians, watchmakers, and model builders all face the same frustration: standard hardware springs are simply too large for compact mechanisms, delicate assemblies, and miniature devices. These mini compression springs are engineered specifically for those tight-space applications where every tenth of a millimeter matters.
Each pack contains 10 identical springs made from 304 stainless steel wire with a diameter of 0.2 mm (approx. 0.008 in). The outer diameter (OD) is available in 2 mm, 2.5 mm, or 3 mm (approx. 0.079 in, 0.098 in, or 0.118 in), and free lengths range from 5 mm to 50 mm (approx. 0.20 in to 1.97 in) depending on the variant selected. The open-coil compression design provides consistent linear resistance across the full compression range.
These mini compression springs are well suited for restoring tension in pen mechanisms and retractable tools, providing return force in miniature switches and push-button assemblies, and acting as spacers or cushioning elements in precision model construction and electronics prototyping. Their small footprint makes them a reliable choice wherever a standard spring would simply not fit.
| Material | 304 Stainless Steel |
|---|---|
| Wire Diameter | 0.2 mm (approx. 0.008 in) |
| Outer Diameter (OD) | 2 mm / 2.5 mm / 3 mm — See variant options |
| Free Length | 5 mm – 50 mm — See variant options |
| Spring Type | Compression (open coil) |
| Quantity per Pack | 10 pieces |
| Surface Finish | Natural (uncoated stainless) |
| Spring Rate | See variant options |
| End Type | Open ends |
| Coil Direction | Right-hand |
Measure the inner diameter of the bore or housing where the spring will sit. The spring's OD should be slightly smaller than the bore — typically 0.1–0.2 mm of clearance is sufficient. For example, if your bore is 2.2 mm, the 2 mm OD spring is the correct choice. If the spring is meant to slide over a shaft instead, the shaft diameter should be smaller than the spring's inner diameter (ID), which is approximately OD minus twice the wire diameter.
The free length is the uncompressed length of the spring. You should choose a free length that is longer than the maximum gap you need to fill when the spring is at rest, and short enough that the spring does not bottom out (reach solid height) before the mechanism completes its travel. If you are unsure, ordering two or three adjacent lengths for testing is a practical approach given the 10-piece pack format.
304 stainless steel offers good resistance to atmospheric corrosion, moisture, and mild chemical exposure. It is suitable for indoor electronics, humid workshop environments, and light outdoor use where the springs are not in prolonged contact with saltwater or strong acids. For marine or highly corrosive environments, 316 stainless steel would be a more appropriate choice.
Yes. 304 stainless steel is non-magnetic (in its annealed state) and has moderate electrical conductivity, making these springs suitable for use as contact elements in low-current switch assemblies, battery contacts in small devices, and similar applications. For high-current or highly conductive applications, a beryllium copper or phosphor bronze spring would be more appropriate.
Spring rate (force per unit of compression) depends on wire diameter, OD, and number of active coils. With a 0.2 mm wire diameter, these are light-duty springs designed for low-force applications such as pen mechanisms, small switches, and model assemblies. They are not intended for heavy-load mechanical systems. If you need a specific spring rate, contact us with your load and deflection requirements so we can help identify the best variant.
The outer diameter determines how wide the spring is. A larger OD generally means a slightly stiffer spring (more coil material per turn) and requires a wider bore to fit. The 2 mm OD is the most compact and fits the tightest spaces; the 3 mm OD provides a bit more lateral stability and is easier to handle during assembly. All three share the same 0.2 mm wire diameter, so the force differences between sizes are modest — the primary selection factor is the bore or shaft size of your application.
Each listing is sold as a pack of 10 identical springs. All 10 pieces in a single order share the same wire diameter (0.2 mm), outer diameter, and free length as specified by the variant you select. If you need multiple sizes, simply add each desired variant to your cart separately.
