What do screw descriptions mean?

[BrowningB]

I would like to know what the following two screw descriptions mean.

14 - 10 x 50mm

4 x 25mm 

There is also the same sort of description for 'pop rivets'.

[MitchellMc]

Hi @BrowningB,

Let's use Zenith 14 - 10 x 50mm Galvanised Type 17 Batten Bugle Head Timber Screws as an example. This indicates it's a 14 gauge screw with 10 teeth per inch and 50mm long. The gauge of the screw is the internal shank without the threads.

For your second example, let's use Pinnacle 4.0 x 25mm Black Countersunk Timber Screw. Here, the description simply states the shank is 4mm (8 gauge) and the length is 24mm. 

The somewhat non-consistent labelling from the suppliers is likely adding to the confusion, but I hope that makes sense.

Now, pop/blind rivets are another kettle of fish. Let's use Otter 4.8 x 12.7mm Open Aluminium Blind Rivets. They require a hole 4.8mm wide to fit the rivet body and are capable of gripping a max thickness of 12.7mm. 

You might like to also check out this helpful guide: How to choose the right screw for the job.

Please let me know if you have any questions.

Mitchell