Headphone jack is mainly used in mobile phone stereo design, CD player, wireless phone, MP3 player, digital notebook computer, DVD, digital camera and more.
Although the popularity of wireless headphones continues to increase, wired headphones and their associated headphone jacks are still used regularly. There are a few different headphone jack sizes we should be aware of when using our wired headphones. These sizes are 2.5mm (3/32″), 3.5mm (1/8″) and 6.35mm (1/4″). The most obvious difference between them is size, the lengths of the connectors are also different. On this page, you can see the 3.5mm snap-in type phone jack.