It appears that ThinMag is being used. ThinMag is a thin, flexible polymer magnetic material (synthetic rubber) that’s available in different colors and can be cut to size. This material is available from Polymagnet, LLC, located in Moscow. In addition, it can be purchased from Arnold Magnetic Technologies which has locations in the US and Europe. Both Polymagnet, LLC and Arnold Magnetic Technolgies belong to the same parent company (AMT&C Group).

References for ThinMag are in the following links:

General Info on ThinMag: http://www.amtc.ru/en/catalog/sheet/thinmag/

ThinMag Sell Sheet: http://www.arnoldmagnetics.com/WorkArea/DownloadAsset.aspx?id=5159

About AMT&C Group: http://www.amtc.ru/en/group/untitled2.php

US Trademark Filing for ThinMag: http://www.tmfile.com/mark/?q=746169069

Potential Patent (US Patent # 05431746): http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=1&f=G&l=50&co1=AND&d=PTXT&s1=05431746&OS=05431746&RS=05431746

Hopefully, this information helps. Best of Luck!