Aluminum zinc alloy sacrificial anode rod made of high-quality aluminum zinc alloy that is key elements for permanently rotten egg smell from water tank. Extends the life of a water heater by attracting elements in the water. If the anode rod is depleted and fully decayed, the water heater begins to rust, then crack, fail and leak. Use with: For Atwood . Unscrew the anode rod to drain the tank. If the rod is mostly eaten away, replace with a new one. Always keep a spare in your RV. Colour: Silver + Black Material: aluminum zinc Size: Diameter width 14mm, length 4.5 inches about 115mm Package Contents: 2 x RV aluminum/zinc anode rods 1 x PTFE tape (the color of the tape is random, don't accept the specified color) Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.