Rugby players wear a variety of items on their backs, depending on the level of play and the teams preferences. Here are some of the items that rugby players may wear on their backs:

• GPS Trackers: Many professional rugby players wear a GPS tracker on their backs between their shoulder blades. This is part of a sophisticated biometric tracking system used by coaches to track a variety of statistics about every player, such as their position on the pitch, speed, and intensity.

• Shoulder Pads: Rugby players may also wear shoulder pads, which are a piece of protective gear worn to help reduce the risk of injury to the shoulder, chest, and upper arm areas during contact or collisions on the field.

• Head Guards: Rugby players may wear a head guard, also known as scrum caps or helmets, to help protect their head and ears during games.

• Base Layers: Rugby players may wear a base layer, which is a Lycra tight compression vest/shirt, under their shirts. This helps to keep them warm and move moisture away from the skin efficiently in cool wet climates, or in warmer climates help to regulate their temperature and keep them cool.

• Tape Strapping: Some rugby players may use extra taping to support shoulder joints that they feel they require.

Overall, rugby players wear a combination of protective gear and tracking devices to help them stay safe and perform at their best on the field.