There are many different sizes of grease gun fittings styles. Commonly there are 2 different grease fitting.
These are the 1/4 ‘’-28 thread and the 1/8’’ NPT thread. However there are also other less common grease fitting threads in use but most common above.

Co-Founder Cord To Cordless
Adan grew up in farmland and learned many things at an earlier age and works in more than 6+ places with different works to gain experience in multiple fields. Currently doing shop projects.
Adan loves to share experiences to build more creativity in your mind.