International Weightlifting Federation: green bumper plates were only officially approved for use by IWF from 1976 to 1980, Montreal being the only Olympic venue where they were deployed. Presently, Olympic plates of or more are in diameter. versions also exist of the lighter and plates to accommodate the proper starting position for beginner athletes. These can be aluminium or plastic and may have rubber edges. Powerlifting As a general rule, powerlifting requires use of stiffer bars to better accommodate the heavier weights being used in the sport. The deadlift barbell is usually the longest, thinnest and the most flexible, thus allowing more weight to be lifted. Powerlifting barbells use simpler, more robust bushings because they do not need to rotate as fast as Olympic weightlifting barbells. Sometimes the sleeves of powerlifting bars are also extended. Additionally, powerlifting bars have their grip marks spaced closer, at . This closer spacing is used to check legal grip width in the bench press. Powerlifting utilizes the same bar for both male and female competitors. The International Powerlifting Federation requires using strictly the same kind of bar on all lifts, being between and in diameter, not more than in overall length, and between and between the inner faces of the collars. Another visual difference from typical Olympic bar or International Paralympic Committee approved one is that the IPF bar's knurling shall not be covered by chrome. Stating that bar should weigh with collars on, effectively permits use of bars only, because same as IWF, IPF requires collars to weigh each. The total weight of the barbell varies based on the type and number of plates loaded onto the ends of the bar and the lift being performed, and easily can be or more with squat dedicated bar (which itself can weigh up to and have up to grip section diameter). Additionally, differently coloured plates are or were used outside of IWF sanctioned competition, most prominently in powerlifting. These include: Powerlifting plates in contrast to Olympic lifting ones are usually thinner (to accommodate more plates on bar) and as they are not meant to be dropped, do not need to utilize additional coating. plates are fairly rare, typically only used in some of the powerlifting federations still using plate sets scaled in pounds, such as IPA, SPF and their affiliates. Black polyurethane coated plates were introduced by Eleiko in International Paralympic Committee sanctioned London 2012