That’s the whole gunLower parts kit, bolt carrier group, buffer and spring, gas tube and all the pins, furniture, barrel and extension, gas block, upper receiver, lower receiver, buffer tube.... at minimum
I'll list a few items:i don’t want to be caught without a spare part in the event of unexpected breakage.
The problem with spare parts is you get tired of looking and not using them.
So you end up using the spare parts to build another blaster.
Which means buying more spare parts, it’s a vicious cycle......
It is amazing how whole rifles accrete around a spare trigger, a spare BCG, a spare forend.