Finally there are shown two safeties. In this case they are distinguished as "free safety" (FS)—also known as "weak safety"—and "strong safety" (SS). The strong safety is on the side following the strong (tight end) side of the balanced offensive line (see above), and has responsibility for covering (guarding as a pass receiver) the TE, while the free safety has no such coverage assignment. However, the coverage played by defense does not always easily allow assignment of such distinct names for safeties. A formation with more than two safeties could have them described by their relative geometric placement—outside, shallow, deep, etc.-but such is not general practice; however, see the discussion of the "nickel" below.