Please help identify these motor parts

[billdz]

Someone gave me a box of rocket stuff but I can't identify the parts in the attached pic. The black and silver tubes appear to 54mm spacers, but they don't look like my AT or CTI spacers. The part leaning on the screwdriver looks like an AT forward closure, but it has no threads. The black ring has threads that screw into a 54mm casing, but there is no retainer ring.

What do I have?
Thanks,
Bill

 

[dhbarr]

54mm RAS
http://www.aerotech-rocketry.com/up...3d1-696ae0787765_54mm_reload_adapter_inst.pdf

 

[billdz]

Yes, that looks like it, thanks. Except why do my spacers have different lengths?

 

[eggplant]

Yes, that looks like it, thanks. Except why do my spacers have different lengths?

I think the shorter one is needed to adapt down from the 54/2800, which isn't a standard "grain length" case.

 

[jimzcatz]

I think the shorter one is needed to adapt down from the 54/2800, which isn't a standard "grain length" case.

Correct.