The stamp on the back notes a manufacture year of 1970, so we'll call this "New, Old Stock". It also notes the manufacturer's code, Factory 3522.

The PLA was unusual in staying with stick-type grenades as their primary infantry hand grenade until fairly recently. One can still see load bearing gear issued to some PLA troops (especially lower priority units) which has grenade pouches designed to carry this pattern of stick grenade. 

The bag would have been standard issue for PLA troops since the 60s, having the same basic design philosophy and reach as the ubiquitous 'Chicom Chest Rig'. Good for a Vietnam look, Sino-Viet border conflicts, that kind of thing.

The wooden training grenades are painted, so the 'screw cap' doesn't actually come off or anything like that. They are just a lump of kindling designed to mimic the real-deal for training. They look pretty cool arrayed in the bag though. 

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