What Am I Riddles

Question: I'm heavy but not backwards.

What am I?

Question: It breaks away from its pack. It creates holes in its victims. It can travel for miles and then disappear. It is part of a dying breed. What is it?

Question: I come in many different colors. I create boundaries to keep things concealed and safe. My best friend is a lock and I am also made of different materials as well. I love to travel: you can find me anywhere. What am I?

Question: Those who make this item, don't use it. Those who BUY this item, have no need for it. But those who USE this item, never see it. What is the item?

Question: What can be white and yellow at the same time?