Homedics Back Massager with Heat, Shiatsu Elite II Heated Neck and Back Massage Cushion. 3 Different Massage Styles and 3 Massage Zones. Comes with Controller and Chair Straps

The HoMedics Shiatsu Elite II is made for those who want massage relief without investing in a full chair. It’s compact, portable, and works well with almost any chair. The cushion provides surprisingly strong pressure, easily reaching deep knots and easing tension. 

If you look for alternatives, check out the Zyllion Shiatsu Massager - still compact and easy to carry. Another smart option is the COMFIER Shiatsu Massager, which combines adjustable rollers with a flexible back pad for better coverage.