Various Guards.

[Andre]

The "Cross-Arm" Guard

The cross arm guard is a "hands and arms high" defensive posture. For right handed fighters the left arm protects the body, while the right is responsible for protecting the head. Among its most prominent users were fighters such as Archie Moore, Joe Frazier and in instances Sugar Ray Robinson.

As a defensive posture the cross arm serves well. With educated movement, this guard can provide a shield for both body and head.
It does however prove problematic when attacking.
By nature the "cross" locates the hands on the opposite side of the body, meaning counter punching is difficult and handspeed is handicapped. Speed is limited as the fighter must draw his hands to a punching position before releasing his punch. In close an adequate defence was established, but again hand position needed to be altered in order to exchange.

Fighters such as Frazier and Moore "filled the gaps" during their opponents rest periods with their own punches, while crossing their guards when the opponent attacked, self preservation is not at the heart of this defense, as damage will be accumulated.

This style is now fading, with more modern trainers insisting the hands must be held either loose to the sides or vertical. However this instructional video will demonstrate the technique.
http://www.youtube.com/watch?v=VXNzF0OGhrM

That style but more squared up; I think can be great nose to nose ,only if he is squared up too and throwing both hands equally at you (so long as he doesnt re distance and start to throw straight shots).But then you just pull a leg back into the stance thats shown)

This cover allows you to use the elbows against his wrists as he tries to come around your gloves,so he pays for a few shots too.

I personally think to use this stance so that you are prepared to move further into a shot from this position (after you've checked him with the same side elbow fold your glove out and push through his arm on that side) so that you move in too and crack them open on that side as his arm returns you follow it bodily, open your stance up and you get into the correct line to get a shot off with the then free inner hand. As you move to that side; your body moves across behind the glove that remains centre so that it is then automaticly freed up from being across you and can fire from its original side as you move through the opposite way .
This makes you beat him to the draw as your hand is on the inside of his other free arm so you win cause your head is hidden behind your attack.
hope that made some sence.