silicone cup for massage therapy (Britannia)

A physiotherapist used one of these on my arthritic knee, and it seemed to help – so I bought my own version.

It came in a pack of two, and this one is too large for that particular spot – I've never used it.

(If you want to know how this thing works, just Google it. FYI, the pic showing a whole bunch of them is just for reference – I only have one to give away!)