In order to keep snow, rain, and other fouling out of the barrel when being carried on the march (where it could cause a potentially life-threatening bore obstruction), Swiss service rifles were historically issued with muzzle covers. The exact designs varied over the years, but broadly fit into two main categories: those for infantry rifles, and those for carbines. The part of the muzzle cover in contact with the barrel is made from a softer metal - either brass or aluminium - to guard against damage to the crown of the rifling.
Due to the front sight being mounted back from the muzzle, the infantry rifle muzzle cover is reasonably long, which makes it easily identifiable relative to a carbine version. There are a number of sub-variants, but all include a brass cup to go over the muzzle itself, and a long tab, cover and hoop to clip over the front sight and simultaneously protect it and secure the cover in place.
This style of muzzle cover will fit the Ig. 89, Ig. 89/96, Kad. Gw. 97, Kurz-Gw. 00, Ig. 96/11, and Ig. 11.