* These rubber gaskets ensure the ATTs alarm head retains the highest level of water resistance. Always replace the existing seal if there is any sign of damage/wear. * To ensure the best possible fit, carefully position the new seal in the recess making sure that it sits flush (untwisted). Then lock down the back plate by tightening opposite corners (see video for more details) for the best possible seal. * 3 x ATTs Gaskets per packet.