Anyone know what this is?

[westcoastgrandnational]

this came with my 87 GN, previous owner had no idea what it was either, its a little device called a "whistler" thats mounted close to the duage cluster, anyone know what this does, it always either shows a "h" a "3' or a "4"??? Can i remove this?

 

[greeneyegi]

picture?
turbo timer,or a radar detector?

 

[Squid4life]

Whistler is a name brand of radar detector IIRC. Yeah, pic would help.