Here are caps from Trekcore.Com showing detail of the red and knit cadet uniforms.
The cadet uniforms may be a wool gab with what appears to be an ornate mock turtleneck sweater-knit shirt. The jacket and pants have what may be 3/16th - 1/4" soutache. On the back, the soutache goes up the back of the sleeve and down the back of the jacket the way the TWOK cord did.
The above is from the Arclite Theater display. Note the insignia improperly placed on the chest, not on the left collar.
In the "Kobayashi Maru" simulator, the cadets wore these jumpers:
I thought the sim room outfits were blue, but are apparently grey and dark grey rib knit fabric.
From the upcoming auction in Vegas next year