Stand with feet close together (narrow stance) holding a barbell across your upper back. Keep your chest up and core braced. Push your hips back slightly and bend your knees to lower into a squat, keeping weight through your heels. Go down until your thighs are at least parallel to the floor, then drive through your heels to stand back up.
Log your barbell narrow stance squat sets in 1RM.fit and watch your estimated 1RM update automatically as you get stronger.