Whether a toupee for men can be straightened depends on the specific material and construction of the unit.
Human hair toupees generally have more versatility when it comes to styling, including straightening. Just like natural hair, they can be heat-styled using flat irons or other heat-styling tools. However, it is important to use heat protection products and set the tool at an appropriate temperature to prevent damage.
On the other hand, synthetic hair toupees are made from synthetic fibers that may not withstand high heat. Most synthetic hairpieces cannot be straightened with a flat iron or curling iron without risking melting or damaging the fibers.