This is the king arms gbb tws. It’s all stock. I haven’t played too many games with it but it looks pretty worn because the king arms paint sucks and just rubs off with just normal handling. It has an issue where the trigger won’t reset in single fire sometimes. Fiddling with the selector switch will reset the trigger. Honestly I probably put something in wrong with the selector switch. It might be an easy fix. I don’t know. That is the only issue. Things I’ve done to it. I put sealant on the back of the bolt because the o-ring only seals when the spring is under tension. If you don’t like it you can just peel it off. I put thumb screws on the hand guard because taking out the flat screws was a pain to adjust the hop up. I took the spacer out of the magazine so it will hold 50 instead of 30 but without the spacer the spring in the mag isn’t strong enough to activate the bolt hold open on empty.(the spacer is in the box. You can put it back in if you want.