 Complete the following phrase:  During the 1970s and 1980s, before specially adapted riot helmets were introduced, officers were expected to conduct public order and crowd control in the standard beat duty helmet. The cork construction provided little protection against attack and thrown missiles. In order to provide more protection, the construction of the helmets changed. Visually they remained the same, but instead of being constructed of cork they were now made out of a very hard-wearing plastic material and covered in felt. Internally they were padded with foam fitted into the shell of the helmet with a webbing-style harness to allow it to sit on the head in the correct manner. Two chin straps were added at this time, a thin leather strap for normal duties, and a public order strap which was made of thick material and included a chin-cup to securely hold the helmet on the head. As well as these changes, helmet plates were altered so that the fixings on them were no longer lugs, but were prong-type pins which were inserted into the helmet and spread apart, so that if the helmet plate was hit by a missile, the lugs would not cause injury to the wearer. Although NATO riot helmets replaced the Custodians for public order, Custodian helmets are still currently used to control football crowds, and protests. As late as 2011 police used Custodian helmets for public order as riot gear was not available, for example during the 