ShZ Acoustics Packs...This has been the best from 2008 to now... And you'll never forget...I'm using the type 1 on my w610 and i enjoy my phone after all these years and new phones getting released...*Type 1: This type of acoustics is for phones with normal equalizer & loud voice for the earspeaker & loudspeaker.*Type 2: This type of acoustics is for sliding phones with normal equalizer & loud voice for the earspeaker & loudspeaker. *Type 3: This Type of acoustics is for phones not having megabass. So you would have a great bass using this acoustic when connecting the handsfree or headset.*Type 3: This Type of acoustics is for Sliding phones not having megabass. So You would have a great bass using this acoustic when connecting the handsfree or headset.