From Sonic Retro
The Combine Ring (コンバインリング Konbain Ringu), also known as the Hyper Ring (ハイパーリング Haipā Ringu), is a rare monitor power-up that has only appeared in Chaotix and Sonic Mania so far. Its icon is represented by a dark blue ring.
In Chaotix, the first game to feature the item, breaking open a monitor containing the item will combine all of the player's Rings into one larger ring. To indicate this, the Combine Ring's icon will be displayed at the bottom of the screen and will stay there until the player takes damage. Upon taking damage, they will drop the large Ring, which will give back all of the Rings they just lost after taking damage. They only have a few seconds to get the large Ring, as it will eventually burst into the usual shower of Rings if they are not quick enough to retrieve it.
The Combine Ring would not be seen again until its return in Sonic Mania, where it is now known as the Hyper Ring, though its function is slightly different than before. When the player obtains the item, the Ring counter in the HUD will turn blue and display a blue ring to indicate that it is active instead of displaying the monitor's icon at the bottom of the screen. Instead of dropping a single large Ring worth all of their Rings, the player will drop up to eight large Rings upon taking damage, each worth a fraction of the player's total Ring count. These Rings will eventually fade away like regular Rings instead of exploding.
Interestingly, if the player has collected more than 100 Rings and has earned an extra life from doing so, they can recollect the larger Rings and earn another extra life from collecting 100 Rings.
The Combine Ring does not appear in any capacity in Sonic the Hedgehog CD, but its icon exists for an unused monitor in the game. However, should the player spawn the blue ring monitor using Debug Mode, breaking it will have no effect. In the 510 and v0.28A prototypes, the monitor would simultaneously give the player Invincibility and Power Sneakers similar to the "S" monitor, while in the v0.51 and v0.70 prototypes it would function like an invisible Shield, allowing the player to take a hit without losing their Rings, and even stack with a regular Shield.
The Combine Ring's icon would also be used for a different monitor in LEGO Dimensions that awards the player 20 blue rings when cracked open.
Obtaining the Combine Ring in Chaotix. Its icon appears on the bottom when active.
Obtaining the Hyper Ring in Sonic Mania. The Ring count turns blue when active.
The monitor that uses the Combine Ring's icon in the 510 prototype of Sonic CD.