For lady underwear fabrics, 

commonly it is to use 95%bamboo5%spandex 150gsm, 160gsm (Ne40/1+ 20D) or 190gsm(NE40/1+30D). 

 

For gentlemen underwear fabrics, 

commonly most is to use 95%bamboo5%spandex 190gsm (NE40/1+30D) or 210gsm(NE32/1+30D). soft is most important for underwear.  

also some use 68%bamboo27%cotton5%spandex 190gsm (NE40/1+30D)  or 210gsm(NE32/1+30D) .

 

commonly the fabrics with is 165-170cm wide.