Here is the link for the adapter for the Akela.
https://donnyfl.com/products/benjamin-akela-1-2-x-20-unf-adapter-a8?_pos=1&_sid=20ec88357&_ss=r
I recommend the Sumo 1/2x20 for the Akela. Get the size that is 1/2 cal higher suppressor to avoid clipping the moderator. For a .22, get the .22/25.
https://donnyfl.com/collections/ldc/products/1-5-x-6-5-inch-sumo?variant=42950065412