Ring (Mario Kart series)
From the Super Mario Wiki
A ring is an air-based, speed-boosting object that first appeared in Mario Kart 7. They are typically found on longer gliding segments and provide a boost of speed when the player drives through them, but can also be found on regular jumps and act as air-based Dash Panels. While the design of the rings varies between games and courses, they all share the same unique sound when glided through, similar to the ones made by the Launch Stars in Mario Kart Wii's Rainbow Road. They function almost identically to the Plane Zippers from Diddy Kong Racing.
Mario Kart 7
Rings first appeared in Mario Kart 7 where they only appear in Rainbow Road and resemble golden Launch Stars and the ones seen around Dash Panels on the track. A total of seven appear in the course, one in the gliding segment off of the planet's rings during the second section of the track, and the other six appear in the section after the spinning tunnel in the third section. The rings on the third set can either be reached by gliding through them or jumping off certain boosted Ramps within the segment.
Mario Kart 8 / Mario Kart 8 Deluxe
Rings also appear in several different courses in Mario Kart 8 and Mario Kart 8 Deluxe. Three appear in the jump section near the start of Dolphin Shoals, which are yellow and have four pointed sections coming off them. These rings are reached by jumping from the ramps beneath them, and the Dolphins will occasionally jump through these rings. Another three appear on the ski-jump like gliding section towards the end of the third section of Mount Wario. These rings are silver with orange parts which say "Mount Wario" in white writing and a propeller on the top which is attached to the ring by an orange exclamation mark in a blue oval. Two more Launch Star-style rings have been added to the first gliding segment in the first section of N64 Rainbow Road. Another pair of rings appear in Big Blue, where they appear on the second jump of section two, and are similar to the Mount Wario ones in design, except now reading "Big Blue", lacking the exclamation mark and using a more futuristic looking design, with the blue antigravity glow due to the section being in anti-gravity.
Mario Kart Tour
Yellow rings appear in Mario Kart Tour in the Ring Race bonus challenges. They provide a small burst of speed when passed through, and the player is required to pass through a certain number of rings in order to pass the challenge. In addition, rings with a blue star design known as Star Rings appear in SNES Rainbow Road R/T; when passed through, points are awarded.