Culligan EZ-Change filter system for installation under the sink to improve water quality. Produces healthier better-tasting drinking and cooking water. Easy twist-on twist-off design mechanism that does not leave a mess. Quick-connect fittings - double water shut-off. Under sink water filter is NSF Certified. The battery is installed behind the faucet. There is a lip there with a battery insert. Putting the battery there powers the indicator light on the faucet. The Culligan US-EZ-4 Under Sink Filter System includes: Filter head with built-in bracket Culligan RC-EZ-4 replacement water filter cartridge Mounting screws Supply adapter Lead-free faucet with built-in electronic cartridge life indicator. Battery included. 1/4 Plastic tubing Filter change reminder sticker Installation Instructions.