All about glass > BRNS Bullet Resistant Glass Classification

If no spall is ejected on the side opposite the shot, the rating is followed by the letters NS

EN 1063 Class	Plastofloat	weapon used	Calibre	ammunitions used	shooting distance in m.	impact velocity in m/s
BR 2 NS	P 139	handgun	9 mm luger	cylindro-ogivale plomb chemise acier plaqué	5	400
BR 3 NS	P 185	handgun	0,357 magnum	conique plomb chemisé acier plaqué	5	430
BR 4 NS	P 278	handgun	0,44 rem mag	cylindro-conique tronquée plomb chemisé acier	5	440
BR 5 NS	P 345	gun, rifle	5,56 X 45	cylindro-conique plomb masse pénétrante acier chemisé acier	10	950
BR 6 NS	P 375	gun, rifle	7,62 X 51	cylindro-conique plomb chemisé acier plaqué	10	830
BR 7 NS	P 730	gun, rifle	7,62 X 51 perforating	cylindro-conique acier chemisé acier(noyau dur)	10	820

For example P 129 stops a 9 mm Luger shot with a handgun from a distance of 5 metres and is rated BR2.
Moreover, because it protects people located just behind the glass by guaranteeing that no spall is ejected, it is rated BR2 NS.