Sooner or later you will be wailing on a guitar solo and snap a string.
If your Eric Clapton you will have a spare guitar ready and a guitar tech to do it for you.
Below is a video I made which shows you just how to do it. It works with both acoustic and electric guitars and will give you a neatly strung tuning post and a guitar which stays in tune. Next time you need new string or break a string have a go yourself