Reports from the field indicate that combat troops find the new monocular PVS-14 night-vision goggle a major improvement over the earlier model  PVS-7 binocular goggles. The PVS-14s are lighter and leave one eye free (and with a wider field of view). Some rifles have a rail on top that allows the PVS-14 to be mounted as a night scope. And troops using 4x ACOG scope can mount the PVS-14 in tandem with it. Troops without a rail on their rifles, found some success by just taping the PVS-14 to the top. There were, however, some negatives. The swing arm and detent button often failed, as did the cover to the battery compartment. The troops also wanted every infantryman to have a PVS-14, but thought they could get by with one per fire team (4-5 men). Some units kept their PVS-7s and, along with the new PVS-14s, were able to give everyone in the infantry squads a night vision device. The profusion of night vision devices made it impossible for the Iraqis and Afghans to successfully use night attacks. This was a major blow, as the weaker force depends on surprise night attacks to even things up a bit.