It was common practice in Vietnam for everyone in a patrol to carry extra 7.62mm link for the GPMG M60. To protect the link from the jungle conditions ie keep it dry and clean, mattress covers (green) or inners (black) were sometimes cut to carry the link. I deliberately left a hole in that one so the link could be seen. I tried for the "start of a patrol" look which is why everything is relatively clean. There is actually 50 rounds of link in that belt, from a Hong Kong manufacturer who makes individual rounds and link that has to be assembled like the real thing.