A video with more information about the bungee anchor is on instagram.

You can order the Bungee Anchors here: SlackX Order Form

In the past years I came up with more and more versions of Bungee Anchors so it got quite confusing. Therefore I decided to not differenciate the Bungee Anchors through different versions, but identify them by two parameters: The length of the bungees and how many layers of rubber it has. 

The length of the Bungee Anchor defines how much extra bounce you add to the Slackline, and the number of rubber layers defines at which range of tension you want to use them, which mainly depends on the length of the line.

For comparison I have a list of the previous versions and how long they were and how many layers they had:
BA1 (for 20-30m lines) Max extension length: 3m and 28 layers of rubber
BA2 (for 30-40m lines) Max extension length: 2.5m and 34 layers of rubber
BA3 (for 35-50m lines) Max extension length: 2.5m and 38 layers of rubber
BA4 (for 40-50m lines) Max extension length: 2m and 40 layers of rubber
BA5 (for 50-55m lines) Max extension length: 2m and 44 layers of rubber
V5 (folded for 50-55m lines) Max extension length: 4m and 22 layers of rubber
V5+ (folded for 50-60m lines) Max extension length: 4m and 24 layers of rubber
V6- (folded for 55-65m lines) Max extension length: 4m and 26 layers of rubber
V6 (folded for 60-75m Lines) Max extension length: 4m and 28 layers of rubber
V6+ (folded for 65-80m lines) Max extension length: 4m and 30 layers of rubber

The price is always for a set of two bungees, you can also buy a single bungee or other custom made bungees, just contact me in this case. 

V-Shape, folded, doubled or straight setup? 
The longer the line gets the more layers of rubber you want to have in your Bungee Anchors, however it's not possible to get more than 42 layers in the sleeve. To be able to have more than 42 layers you can take two Bungee Anchors parallel so the number of layers add up, or you take a longer bungee and fold it in half, to double the number of rubber layers. 

Bungees of up to 32 layers are possible to fold, for the thicker versions its not recommended, because that can damage the Bungee Anchors.

V-Shape or completely folded?
V-Shape is a bit more complex to set up, therefore it has theoretically the advantage that the bounce is a bit more stable and less surfy, however when setups slightly unsymmetrically it actually makes the line surf as soon as you start bouncing, therefore I don't recommand this method anymore. 
I would recommend to just completely fold the bungees and rig it off one masterpoint. 

The length range given in the brackets is an indication for which length you have the best performance of the Bungee Anchors for freestyling. 

Your weight and your bounce preference has an influence what you should choose if you are in between two versions.
I was assuming an average weight of 70kg, if you are (much) heavier you should tend to a version for longer length.
If you are lighter you should tend to a version for shorter lengths.
If you like a lot of "pop" at the highest point you should tend to a version for longer length.
If you prefer a slower bounce and more time for your tricks you should tend to a version for shorter lengths.

What happens if you use the Bungee Anchor out of the recommended length:
If you use Bungee Anchors on shorter lengths than recommended, you can reduce pretension, so you will have a lot of sag and the bottom of the bounce is getting a bit harder.
When you keep the pretension rather high you will have a lot of "pop" at the highest point which can also lead to getting airtime at the highest point. The bounce is quite fast. It's then more a mix of freestye and trickline.

If you use Bungee Anchors on longer lengths than recommended, you can leave the tension quite low, which means you have not much "pop" but therefore a big and slow bounce.
If you add more tension you risk that you will max out the bungees, then you will have suddenly a very hard bottom, which is not comfortable at all and makes freestyling basically impossible. You shouldn't keep freestyling or walking on a line where you max out the Bungee Anchors, either change the Bungee Anchors or reduce the pretension to avoid hitting the hard bottom. 

I hope this is enough help for you to choose the right version. Otherwise feel free to ask.
I am also trying to understand better the physics behind bouncing, and calculate the bounce behavior. I hope in the next weeks/months I can post some more insights and graphs.

Polyester, Nylon or Dyneema webbing?
That's a good question which still needs more testing. For now I would recommend for lines shorter than 55m Nylon, because it still gives you more bounce. But polyester has some advantages over nylon, it is more durable, often cheaper and doesn't change behavior when it gets wet. With polyester you tension it once to the preferred tension and then you don't need to do anything anymore with the rig. 
Dyneema has the same advantages of polyester, besides being quite expensive, but therefore it's really strong super light and will last for a very long time. The longer the line is which you want to rig, the more important is it to have a light set up. The problem with dyneema is that the handling is difficult, because it often doesn't work in weblocks or linegrips. Also it has basically no stretch so all the bounce needs to come from the bungee anchors. If you use dyneema webbing you want to choose a longer Bungee Anchor

Some general information to the bungees:
They are all a bit longer than 1m and each weights around 1kg.
I don't want to give a MBS for the Bungee Anchors, because there are still too many unknowns, especially how they are degrading and if the interactions between the different materials under cyclic loading can have negative effects. A simple pull test on a new product has very limited meaning on how strong the bungees are after longer usage.
So the Bungee Anchors must always be used with a strong backup. Industrial 1t WLL slings are perfect, otherwise I offer 6mm dyneema slings as backup. The backup must be the same length as the maximum effective extension length. (if you use a 4m bungee anchor and fold it in half, the effektive length is 2m) 

The numbers are for now only guidelines, it also depends a lot on your personal preferences