# Threads

There are a few different thread types out there. They are not necessarily interchangeable, and some uses two different names.

The most common thread standards are:

* BSP - British Standard Pipe
* NPT - National Pipe Thread
* M - Metric threads

BSP exists in two types, BSPP and BSPT. The last letter indicates the shape of the threads.

* BSP**P** - **P**arallel
* BSP**T** - **T**apered

Sometimes different names are used for the same thread type. As an example, a 1/2" BSPP can be sold as G1/2". Similarly a 1/2" BSPT can be sold as R1/2".

The picture below illustrates all of this. As you can see, a BSPT male thread will mate with both a BSPP and BSPT female thread.

![](https://3668380214-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-MIsW5sFFK20mPqMKRG6%2F-McxfkhbIxWEbrVVObWS%2F-McxleA0tVnKTee8yyVi%2FFitting%20Threads_2.jpg?alt=media\&token=e5dfa575-38ea-4fd3-9c44-a44d5a61e685)