The round is the back leg, and it trades in pieces. Four boneless subprimals carry the market: the top inside round (IMPS 168, with trimmed variants in the 169 family), the outside round flat (171B), the eye of round (171C), and the knuckle, also called the sirloin tip (IMPS 167, usually traded peeled as 167A). The report also carries the bottom gooseneck round, which is the outside, eye, and heel still together as one untrimmed piece.
What each piece does
The inside round is the biggest single muscle and the deli backbone: roast beef programs, sliced sandwich beef, and thin-cut retail lines all spec it. The outside flat is the braising and commercial roast piece, a step tougher, and a workhorse for cooked roast beef manufacturers as well. The eye of round is the neat cylindrical muscle that presents well sliced, so it splits between retail roasts and further slicing. The knuckle grinds and cubes: sirloin tip steaks, kabob and stir-fry cuts on the retail side, lean grind raw material behind that.
How the ladder trades
Price-wise the round is a compressed complex: its pieces trade closer together than the chuck's or the loin's, because everything in the round is lean and everything competes at the value end of the case. Over the last five years the inside has held only about a six cent median premium over the outside, and it has traded above the outside on just 63 percent of days. The premium is real but thin, and it flips regularly.
That flip is the read. The inside is the deli muscle and the outside is the braising and manufacturing muscle, so which one leads says which channel is bidding the round. The gooseneck, being the outside and eye still combined, trades at a natural discount to the fabricated pieces and prints thin, so treat its quotes as a manufacturing-trade footnote rather than a daily signal.
That grind linkage is the round's defining feature: it is the primal where the whole-muscle market and the lean trim market meet, which is exactly why round quotes move when cow slaughter tightens even if no deli program changed its order.