The Petite Tender is a little muscle from the front shoulder. Because it's small, butchers try to trim them without losing the size of the cut, which means occasionally there are some tags of connective tissue on an edge. If you see white bands of connective tissue on the edge here or there it is a good idea to remove them before cooking so they don't distort the shape of the cut as they shrink in the heat. Petite Tenders, along with the Flat-Iron and Denver, are the only grilling/frying cuts we take from the chuck (shoulder).
Be careful when buying "tenders" from the chuck. There is another cut called the "Chuck Tender or Mock Tender" that is anything but (we sell them as Medallion Pot Roast to try avoid confusion). Petites are in fact fairly tender and lean. In general lean beef is less forward with the BEEF flavor, so this cut tends to run on the mild side.