Ultra-rare 8-track blank tape set of 3 for tape echo, etc.

This is an unopened 8-track blank tape, a rare find. How about it for those who own an 8-track tape echo? Since 8-track tape echo machines are analog equipment, the sound quality changes significantly depending on the condition of the tape. Please consider this if you are reusing old tapes. However, please note that the shape of the tape insertion slot often does not match, so modification may be necessary in such cases. This is recommended for those who can open the cartridge and modify it. This is a set of 3 tapes.