A Karate stance
named after the Kata
Naifanchi in which only this stance is used.
It is formed by first standing with feet shoulder width apart, and then turning both feet inwards by about 15° degrees. The knees are bent slightly to prevent premature creaky arthritic problems
The correct distance between the feet is equal to the length of your lower leg from ankle to knee, and the width of two fists. No really, I'm not making this up, what you do (to check, not during a Kata or something) is from Naifanchi dachi turn one knee in so that you're kneeling with one knee placed beside your other foot but without moving your foot of the kneeling knee, and then get both fists one after the other, between the knee-other foot gap and then close up any remaining space by moving the foot in to touch the 2nd fist. Then stand up again, and reassume Naifanchi dachi. This is the correct width.
This stance is handy also for forming (and indeed working with) the Seishan
stances. It is a mid-width stance and the bent knees make it quite strong for applying forces perpendiclar to the direction you're facing, and at up to about 30° off facing. It's not so good for punching straight ahead unless you're skilled at finding strength from nowhere