Marker

The Marker (マーカー), also referred to as the Arrow Monitor (ポイントマーカー) is a Monitor power-up that appears in the Sonic the Hedgehog series. When obtained, the players' progress up to that point in a Zone will be saved, so when the player loses a life, the playable character will start over from the last Marker they opened.

Description
The Marker is an old-fashion Monitor with a red or orange "↓" icon on its screen.

Markers function as check points for each point of their respective Zones. When the player opens a Marker's Monitor and loses their life or gets time out afterward, the playable character is returned to the spot of the last Marker they opened where they will start the gameplay over from the point in time the Marker was opened. This does not apply when the player gets Game Over for losing all their lives.

Sonic the Hedgehog (8-bit)
The Markers made their first appearance in the 8-bit version of Sonic the Hedgehog (8-bit). In this game, the arrow on their monitors is orange. They are also each referred to as the Arrow Monitor (ポイントマーカー).

Sonic the Hedgehog Triple Trouble
In Sonic the Hedgehog Triple Trouble, the Markers have a black arrow with an orange outline on their monitors. In this game, they are also each referred to as the Marker (マーカー). In gameplay, Markers do not appear in the third Act of most Zones, although one is featured in the third Act of the last Zone, Atomic Destroyer Zone.

Sonic Blast
In Sonic Blast, the Markers have a red arrow on their monitors. In this game, they are also each referred to as the Marker (マーカー). In gameplay, Markers do not appear in the third Act of the Zones, which feature boss battles.