As one who served in the U.S. Army back in the days of compulsory service and finished as a Sergeant, I can tell you that we call them stripes also, although they are technically chevrons. A PFC (Private 1st Class) has one stripe, a corporal 2, sergeant 3, then with various classes of sergeants "rockers" are added on the bottom of the stripes up to Sergeant Major which has 3 stripes and 6 rockers. These are on the upper part of the sleeves. One speaks, in the military, of "losing one's stripes" i.e., being "busted down" to "buck private" (the lowest grade), or of losing a stripe (demoted a grade) or of getting an additional stripe (being promoted). The "hash marks" alluded to by WOW, are short diagonal stripes on the lower part of the sleeve near the cuffs, and indicate length of service.