A black bloc is a tactic used by protesters who wear black clothing, ski masks, scarves, sunglasses, motorcycle helmets with padding, or other face-concealing and face-protecting items. The clothing is used to conceal wearers' identities and hinder criminal prosecution by making it difficult to distinguish between participants. It is also used to protect their faces and eyes from pepper spray, which is used by police during protests or civil unrest. The tactic allows the group to appear as one large unified mass. Black bloc participants are often associated with anarchism, anarcho-communism, communism, libertarian socialism, antifascism, or the anti-globalization movement.