When you need a small compression spring, the first question is whether the size and length will work for your project. A spring that's too wide won't fit the bore, and one that's too short won't provide the travel you need. This 4mm outer diameter, 300mm long compression spring from the various-size range aims to be a versatile pick, but is it the right spring for you?
Compression Spring Various Size 2-42mm Diameter & 300mm Length Pressure Small
Quick Verdict
At $3.69, this spring is a low-cost option for anyone who needs a long, narrow coil. The spring steel construction and open ends make it a basic but functional choice for simple spring needs and DIY projects. It's not a precision component, but for a straightforward spring requirement, it does the job.
Who It Suits
This spring suits hobbyists, makers, and repairers who have a specific space for a 4mm outer diameter coil and need extra length to cut down. It's also a good pick for prototyping or a one-off repair where a standard spring won't do. The open ends are fine for applications where the spring sits in a recess or around a rod.
What Stands Out
The 300mm length is the standout feature here. Instead of being stuck with a short spring, you get a long coil that you can cut to the exact size you need. The 4mm outer diameter is narrow enough to fit many small assemblies, and the spring steel material offers a reasonable amount of resistance for basic tasks.
Meaningful Trade-offs
The open end type is a real trade-off. Open ends mean the coil simply stops without being closed or ground flat, so the spring may not seat evenly against a flat surface. Also, this listing is for a single spring, not a multipack. The price is low, but if you need several springs, you'll need to order multiple units. And while the title mentions a range of diameters, the spring you receive with this listing has a 4mm outer diameter, so keep that in mind if you need a different size.
Bottom Line
If you need a small-diameter compression spring with plenty of length to customize, this 4mm x 300mm option at $3.69 is worth considering. Just pay attention to the open ends and the single-pack quantity. For a low-stakes project or a prototype, it's a practical choice.
