Very rare and hard to find in such good vintage condition! 
Brand: Grove 
Listing includes an advertisement for the Grove TUN-3 / TUN3 and TUN-4 / TUN4 Minituner and the instructions for the TUN-4 or TUN4 minituner. The minituner is a shortwave receiver accessory that provided inputs for 2 antennas and 2 separate receivers and a tunable preselector covering 100khz-30 mc in 4 bands with a separate preamp. 
Please review the photos as they are included in the listing. 
A must for an owner of the Grove minituners! 

Flat rate shipping offered within the continental U.S. only.