Elon Musk has come a long way from his days as the CEO of PayPal, and so has his hairline.

According to Dr. Jeffrey Epstein, MD, a hair transplant specialist in New York and Miami who has not treated Musk, 47, it’s “highly, highly likely” the multi-billionaire tech mogul has had hair transplant surgery.

“If you look at his pictures from his PayPal days, when he sold the company [in 2002], he was pretty bald,” Epstein told Page Six. “I mean, he had a class three to a class four (out of seven) hair loss pattern and he now shows no evidence, at least in the front, of any hair loss.”

The specialist described The Boring Company founder’s early-aughts hairstyle as “significant frontal thinning with recession,” or “the Prince William look”: a moderately recessed hairline with fine baby hairs covering the frontal one-third of the scalp.

Epstein said the tech entrepreneur was a great candidate for hair transplant surgery, as “it looks like he had good hair on the back and side of his head, and those are the hairs we use for transplanting.” He added that the fullest and most natural results come from transplants like Musk’s, where hairs from the back and sides of the head are relocated to the front half of the scalp.

Epstein described older hair transplant surgery techniques, like the one Musk would have undergone, as uncomfortable but not terribly painful. Most patients are fully presentable in about six to eight days, he said, although it can take around six months for the transplanted hairs to fully grow back in after falling out post-surgery.

The procedure also comes with a hefty fee: One surgery can cost anywhere from $8,000 to $15,000. According to Epstein, Musk likely received at least two procedures, setting him back anywhere between $20,000 and $30,000 in total. (Pocket change when you’re the 54th-richest man on the planet, perhaps.)

Epstein added that Musk got “a good result” from his surgery. “Offhand, you wouldn’t know that it was done,” he said. “But when you’re in the business, you know what to look for.”