Used pair of oil pan support rails.  Also called spreader rails, these go under the head of the bolts on factory stamped steel oil pans to spread the load evenly.  1 pair, fits 1-pc small block chevy and 92-97 LT1 engines with factory style stamped steel pans. Fits the following:

86-96 350 TPI/LT1 Corvette
86-97 305/350 SBC/LT1 Camaro & Firebird
94-96 LT1 Impala SS

The item in the photo is the exact item being sold.