President Donald Trump likes to talk about his border wall, and he bragged this week about its efficiency, saying that only Olympic-level immigrants could get over it.

“Now, there may be the case of an Olympic champion who can get over the wall, but for the most part, you’re not able to do it. Very high, it’s going to be 30 feet, much of it is 30 feet high, some of it’s lower. In some areas we have it as high as 30 feet. That’s as high as a three-story building.”

On Wednesday, Trump signed his name on a newly constructed section of the U.S. border wall in San Diego, and called it “world-class security system.”

It was reported he dropped a preference for a solid concrete wall, and opted for concrete-filled steel posts so agents would be able to spot assailants throwing rocks or other projectiles.

“It’s the Rolls-Royce version,” Trump said.

According to Army Corps Lt. Gen. Todd Semonite, 66 miles of wall have been built, 251 miles are under construction, and has 163 miles contracted to begin in the next 90 days. Trump said he expects to build up to about 550 miles of wall along the 1,954-mile (3,126-kilometer) border.

High costs caused Trump to forego his plan to paint the wall black. He said the wall was “a good, strong rust color” and could be painted later.

Though Trump claimed Mexico would fund the wall during his 2016 campaign, the Department of Defense has finalized nearly $2.5 billion in contracts as of Thursday.