Thanks for the info Imran bhai.
It seems like this sheet is quite small (500mm x 500mm). Not too much info available on it online either. Probably better to go with Lanbo given the many positive reviews here on PW and the fact that its better value for money?
Regarding the other 3M product you linked to, I know some manufacturers advertise rubberised undercoat for sound deadening purposes as well, but I think its primary purpose is to prevent rust and corrosion. Detail Pro in Karachi is offering a similar treatment (the product is called Raptor Liner - essentially a rubberised undercoating) and even though the info available online would have you believe it can also be used for sound deadening, I think its main purpose is to line exposed truck beds for protection from rust, corrosion etc. Hopefully other PW members better informed than me will chime in with their thoughts on this.