Tension Pins, Roll Pins, Spring Pins – call them what you will, they all serve a similar purpose – to secure the position of two or more parts relative to each other (says Wikipedia).

How they work is that they have a body diameter which is larger than the hole diameter they are designed to go into.  So a spring is created as the pin is compressed slightly to fit into the hole diameter it is destined for.  This outward force generated by the pin pushes it against the wall of the hole,  so voila, it stays put.

There are various names for them but 2 main types – a version with a straight cut (Tension Pin) and a type with a skew proof cut (Spring Pin).

It is important to note the grade of Stainless Steel

Most types are made of 420 Stainless Steel as it is easier to manufacture. This is fine for many instances but the corrosion resistance of 420 is lower than that of 304 and shouldn't be used for corrosive environments such as outdoors on the coast or near salt water.  

316 Stainless is ideal for the coast but next to impossible to make into a Spring Pin.  The best grade available would be 304, these would be brought in to order and would come metric sizes.

Here is an overview of readily available Roll Pin types and Pros and Cons of each:

Name	Stainless Grade	Pros	Cons	Availability
Skew Proof Spring Pin - Metric	420 SS	Highest Quality, precision and 'skew proof' wave cut	Lower corrosion resistance than 304 grade	Ex stock Anzor
Tension Pin - Imperial/Inch	420 SS	Fits inch size cavities	Lower corrosion resistance than 304 grade	Ex stock Anzor
Tension Pin - Metric	304 SS	Medium Corrosion Resistance	2 week delivery ex overseas	2 week delivery ex overseas
Light Duty Skew Proof Spring Pin - Metric	420 SS	Light duty for certain applications	2 week delivery ex overseas	2 week delivery ex overseas

Anzor Australia has a wide range of tension pins in stock and also access to a wider range of Wave Spring Pins for Light Duty applications which can be shipped and received in 2 weeks.