In some implementations, an adjustable seal includes a multi-layer strap having a first end and a second end. A first layer of the multi-layer strap comprises a non-sealing material. A second layer of the multi-layer strap comprises a sealing material. The first end of the multi-layer strap includes a locking mechanism on the first layer of the multi-layer strap. The second end of the multi-layer strap is configured to be inserted through an opening of the locking mechanism to cause the multi-layer strap to form a loop that is to provide a seal. The first layer of the multi-layer strap is to form an external layer of the loop and the second layer of the multi-layer strap is to form an internal layer of the loop.