https://github.com/ayeowch/bitnodes-hardware has been updated to enable Bitcoin Core v0.13.1 pruning on the B1 that uses 128GB microSD card and below.
The default pruning value is set at 80% of the microSD capacity (approx. 100GB for 128GB microSD). This will be the max. amount of disk space Bitcoin Core will use to store the blockchain data.
Pruning allows your B1 to continue to operate and support the network without the need to upgrade to an expensive 256GB microSD card.
To apply the update, login into your B1 and run the commands below.