You may have discovered a black box known as a ferrite with your purchase of an Acuva Arrow 5 with faucet. After you’ve inserted the faucet cable into the spacer, install the ferrite. The ferrite prevents the faucet and cable from serving as an antenna, receiving and transmitting feeble electromagnetic radiation that might interfere with communications equipment.
Place the cable inside the ferrite and shut it tightly to secure it. Tape the key to the ferrite or put it somewhere secure so you can extract it if you ever need to alter your installation or remove the faucet. To hold the cable in position, use the provided cable-tie to attach it against the ferrite.