This is a 3-pack of 1/4" standard mono phone jacks. These jacks have a shorter shaft than Neutrik-brand jacks we sell, but they are a good bit cheaper and are great for CBGs, amps and other homemade instruments. The shafts on these jacks are about .30" and can accept a panel thickness up to about .16". They come with a nut and a washer, perfect for mounting on one of our jack plates! These are sturdy, well-made jacks that will serve well for most any standard audio/instrument usage.