what is this?

[nipplez]

http://store.airgun.com/index.cfm?action=cat.prodInfo&productID=373&categoryID=16

what is this and where is it at on a ule body?

[alooney11]

if you look in the body from the back, it is in there, that is the washer the spring rests against.

[nipplez]

i bought the body used, it should be in there right?

[athomas]

Yes. You should probably never have to worry about this part.