President Trump on Thursday said he wants a wall built along the U.S.-Mexico border that is fully transparent, so border agents can see "200 yards out" and easily monitor activity on the other side.

That request would immediately eliminate six of the eight border wall prototypes currently being tested in Southern California.

"If I'm standing here, I want to be able to see 200 yards out. I want to be able to see, I don't want to have a piece of concrete that I can't see," Trump told the Wall Street Journal in an interview.

He continued, "This is going to be [a] state of the art wall. But I can fully understand why you'd have to have vision. I'd like to be able to see three or 400 yards instead of we're at a wall we have no idea who's on the other side."

Only two wall prototypes built in Otay Mesa, Calif., last October would meet the president's standards, as the remaining structures are all made of solid concrete or steel with subterranean features that reach as far as eight feet below ground.

All eight prototypes, which were budgeted at $500,000 each, are currently undergoing a 60-day evaluation period during which U.S. Customs and Border Protection officials will test their ability to withstand severe weather, tunneling and other attempts to breach the structure.

Several CBP officials told the Washington Examiner during a visit to the southwest border last fall that the final border wall project could incorporate a combination of two or more prototypes. It's unclear whether any of the solid structures could be modified to include elements from either of the two see-through mock-ups.

Trump is reportedly planning to visit the construction site for the prototypes following his first State of the Union address on Jan. 30. His administration requested $18 billion from Congress last week to fund the project over the next 10 years.