Epson Progression U12 - Manual (Page 34)

If you have a 3.5-inch diskette drive, insert the diskette with the
label facing up and the metal shutter leading into the drive, as
shown below. Slide the diskette into the drive until it clicks into
place.
release button
metal shutter
When you want to remove the diskette, make sure the drive
light is off; then press the release button. When the diskette
pops out, remove it and store it properly.
Never remove a diskette, or reset or turn off the computer
on. You could lose data. Also,
remove all diskettes before you turn off the computer.
Using Your Computer 1-15