Mö·bi·us strip 
(mœbē-əs, mā-, mō-)
(mœbē-əs, mā-, mō-)n.
A continuous one-sided surface that can be formed from a rectangular strip by rotating one end 180° and attaching it to the other end.
[After August Ferdinand Möbius (1790-1868), German mathematician.]
Möbius strip