What apparatuses are used in Olympic rhythmic gymnastics?

In rhythmic gymnastics, there are five apparatuses used for individual competition: rope, hoop, ball, clubs, and ribbon. Rhythmic apparatuses must conform to specific norms and are officially inspected prior to competition.  

What is a hoop made of in Olympic rhythmic gymnastics?

The hoop must be made of wood or plastic.

Margarita Mamun during the rhythmic gymnastics individual all-around qualification
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What are the dimensions of the hoop in Olympic rhythmic gymnastics?

The interior diameter must measure between 80 and 90 centimeters (2 feet, 7 ½ inches and 2 feet, 11 ½ inches). It must weigh at least 300 grams (10.6 ounces).

What is the ribbon in Olympic rhythmic gymnastics?

The ribbon apparatus is a stick made of wood or synthetic material, from the end of which extends a ribbon made of satin or similar non-starched material. The maximum stick diameter is 1 centimeter (0.39 inches) and the stick length must be between 50 and 60 centimeters (19.5-23.4 inches). The ribbon width is between 4 and 6 centimeters (1.56-2.34 inches) and its length must be at least 6 meters (19 feet, 8 inches). It weighs a maximum of 35 grams (a little more than one ounce). 

 Rong Shang during the rhythmic gymnastics individual all-around qualification
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What are the clubs in Olympic rhythmic gymnastics?

Gymnasts work with two clubs of equal length, 40 to 50 centimeters (about 16-20 inches), which resemble slender bowling pins in shape. Made from wood or synthetic material and weighing 150 grams (5.3 ounces) each, the clubs have a wide end (the body), a tapering middle section (the neck), and usually a ball on the end (the head). 

 Lisa Wang performs her clubs routine
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What are the dimensions of the ball in Olympic rhythmic gymnastics?

The ball must be made of rubber or soft plastic, with a diameter of 18 to 20 centimeters (7 to 8 inches). It must weigh at least 400 grams (14 ounces). 

Salome Pazhava during the rhythmic gymnastics individual all-around qualification
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What is the attire for Olympic rhythmic gymnastics?

Rules regarding attire in rhythmic gymnastics are very stringent. The dress code is specific regarding the cut and fit of the leotard. For example, a gymnast can be penalized for inadvertently revealing a bra strap or if her outfit is decorated in anything other than an abstract design. Forbidden attire includes harlequin and tutu-like clothing. Gymnasts in group competition must be dressed identically. Penalties are 0.20 points for individuals and up to 0.50 points for groups.