What does this do? How to use it?

Note: the transport rings are still an incomplete feature, so all of this info may be subject to change.

A "Ring Panel" is the controller block for a nearby "Transport Rings" block. Together, the two form a long-ranged teleporter network for use within the dimension they're placed.
Note: I'm not sure if it's because I was testing in a creative world with cheats enabled, but the transport rings seem to have infinite range. I set one up at 0,0 and another 10 million blocks away and they connected just fine???

At time of writing ring panels are the only way to initiate a transport ring teleport. That said, only the sending transport rings need a ring panel. The destination rings can receive a traveler without a panel nearby (see below for more detailed info).
Nether device requires power or fuel of any kind. It's just place-and-go!

How to get?
There is no crafting recipe for ring panels or transport rings. they can only be found as part of structures:

• Goa'uld Temple (Overworld)
• Pyramids (Abydos)

Ring Panel UI
The 6 green rectangular buttons in the ring panel's UI correspond to transport rings within that panel's network.

• Hovering your mouse over one of these buttons will display the XYZ coordinates that button will teleport you to.

• If there is no destination assigned to a button it will display [ 0 0 0 ] (3 zeros).

• If the ring panel is placed without a transport ring in range, all buttons will display a single [ - ] (hyphen/minus).

• A ring panel needs a 'sender' ring within range in order join a transport ring network.

• A ring panel only receives status updates about other rings in it's network while it's connected to a 'sender' ring.

• There are 6 item slots on the left side of the panel's UI. These will only accept "Memory Crystals" and can be stored in the panel's inventory indefinitely. This feature is still incomplete and has no practical use yet.

• That said, you can name memory crystals in an anvil and use them as a super expensive nametag to note destination names. But you could also place a sign or lectern next to the panel to achieve the same goal.

Setting up a Ring Panel & Transport Rings
The ring panel and transport rings work similarly to a DHD and Stargate. The ring panel will automatically register the closest transport ring block as it's 'sender' or 'point of origin' to use Stargate terminology.

• A ring panel will search for a transport ring block within a 3x3 chunk radius (centered on the chunk where the ring panel is placed) . if one or more rings are found within range, the ring panel will register the closest transport rings as it's sender, and any subsequent transport rings as destinations.
• That's a max of 30 blocks allowed between the panel and ring blocks on the X & Z axes. There is no height (Y) limitation. The panel could be at build height and the rings at bedrock and they would still connect properly.
• The ring panel will also attempt to register up to 6 transport rings other than it's sender. These 'destinations' are recorded and each assigned to one of the 6 buttons in the panel interface (see above).

Using Transport Rings
When placed, a transport ring block will have large 'ring entities' surrounding the block. When activated, these rings will extend to surround a 3x3x3 block area. The rings pass through blocks and entities without effect making them purely visual.
Any mobs, players, boats, and off-rail minecarts within the ring's target area will be teleported to the destination rings.
Block entities such as chests and signs are not effected.

Note: Transport rings are two way. Meaning entities standing within the target area of both the sender and destination will swap places when a teleport is triggered.

• Transport ring blocks can be placed facing up or down, similar to a dispenser. Based on the block's orientation the ring entities will either rise or descend to surround the target area. The orientation of the block is indicated by the circular texture on it's top/bottom face.

• Transport rings are designed to be placed below the floor, or above the ceiling of a structure and are functional through up to 15 solid blocks. When activated the transport rings will check this column of blocks for viable target areas. For an area to be considered 'viable' it must meet the following requirements:

• A minimum clearance of 1x3x1 empty block above/below the transport rings block.

• There must be at least a 1 'floor' block below the target area. The floor can be a solid/partial block, carpets & string also work.

• For rising rings, the highest possible floor is the 15th block above the transport rings,

• For descending rings, the lowest possible floor is the 19th block below the transport rings.

• If more than one viable target is found, the one closest to the ring block is targeted.

• Note: All mobs within the target area will be teleported. A mob's position in the target area is maintained when teleporting. If the destination is partially obstructed it is possible to teleport into a solid block and begin suffocating.