Used pair of factory LS valve covers that have been modified by someone.  These are considered the "Mid year" series covers.  These are compatible with 99-14 LS engines, but please note the location of the breather ports.  These are casting # 12570696 and 12570697.  The LH cover has a steel nipple, which is the later design (Older design has a hole/grommet instead).  The RH cover has a long breather at the filler neck.  Someone has welded a 1" spacer to the covers for aftermarket rocker clearance.  Covers are sold as shown, just covers.   This will require longer bolts than the factory ones (not included).