10pcs A2(304) Stainless Steel Compression Pressure Small Springs 0.3/0.4/0.5mm

Wire diameter determines the spring's stiffness and load capacity. Thinner wire (0.3mm) produces a softer spring with lower force, suitable for light-touch mechanisms like pen clips or sensor returns. Thicker wire (0.5mm) delivers more force per unit of compression, better for valve returns or actuator resets. Match wire diameter to your required load and deflection using a spring-rate calculation or by testing a sample.

Wire diameter is the thickness of the steel wire used to coil the spring. Outer diameter (OD) is the overall width of the coiled spring body. When selecting a spring for a housing or bore, the OD must be smaller than the bore ID, and the inner diameter (ID = OD minus 2× wire diameter) must be larger than any guide pin you plan to use.

A2 (304) stainless steel offers good resistance to atmospheric corrosion and mild moisture. It is suitable for indoor environments and light outdoor exposure. For marine, high-humidity, or chemical environments, A4 (316) stainless steel would be a more appropriate choice. These springs are not recommended for prolonged immersion in saltwater or exposure to strong acids.

Yes. The small OD options (2mm–5mm) and fine wire diameters make these springs well-suited for pogo-pin test fixtures, spring-loaded contacts, and PCB alignment jigs. Stainless steel is non-magnetic (304 is austenitic), which is beneficial in sensitive electronic assemblies where magnetic interference must be minimized.

Free length is the uncompressed length of the spring. Choose a free length that, when compressed to your working position, still leaves the spring with some remaining travel (do not compress to solid height). A common rule of thumb is to design for a working deflection of 20–80% of the free length. For example, a 20mm free-length spring working at 15mm compression is operating at 75% deflection — within a reasonable range for most DIY applications.

Each variant is sold as a pack of 10 identical springs. To get multiple sizes, simply add each size variant as a separate item to your cart. There is no minimum order beyond one pack per variant.

Spring rate (force per unit deflection) depends on wire diameter, OD, free length, and number of active coils. For these small springs, the rate is not published per variant — if your application requires a specific rate, we recommend ordering a sample pack and measuring deflection under a known load, or contacting us with your load and deflection requirements for guidance.