which direction is "up" to install Volume button cover?

Can this piece be installed upside-down/backwards or is it supposed to go in only one way? I don't think it is quite symmetrical, but since the button fell out I don't know which way to put he new one in. There might be a triangle on one end but it is difficult to tell if is just a mold/cast remnant or if it is a directional indicator. It appears to fit equally unwell no matter which way it is flipped, but it might work better if it is properly oriented .

To make matters worse, the silver cover section has come apart from the plastic black backing which has the marking that may or may not be indicative of orientation and I don't know if that piece is properly oriented on the other either! I have never seen one properly installed because it fell out before it came to me to fix cracked screem and put on a new housing. All of the guides I have seen do not show this part in any detail to tell...

Anyone know if this up/down direction matters, and if so, how to determine which end is which on both the black part and the silver part?

Thanks!