Angels starter Matt Shoemaker explains to OTL why he's deciding to wear protective headgear when he pitches and shares how his recovery is going after getting hit in the head by a line drive. (2:05)

Nearly seven months after he needed emergency brain surgery because a line drive struck him on the right side of the head, Matt Shoemaker said he's "perfectly comfortable" on the mound and has settled on a protective insert in his cap as he returns to the Los Angeles Angels' rotation.

The 30-year-old righty, who is in the running to pitch the team's opener, told Outside the Lines he experimented with four or five headwear products during the offseason and spring training, narrowed the options to two and concluded that the Safer Sports Technologies Pro Performance carbon-fiber head guard is the one that best meets his requirement of increased protection while feeling like a regular ball cap.

Matt Shoemaker will use an insert in his baseball cap this year after being hit by a line drive. Safer Sports Technologies

"It's comfortable to the point that I don't know it's there," Shoemaker said.

During his recovery from a skull fracture and subdural hematoma, Shoemaker said he and his family discussed the possibility of protective headwear.

"I'm completely comfortable not wearing anything beyond a cap," he said, "but I was asked to try stuff -- it'll make others more comfortable -- and if I can pitch as if it's not there, why not?"

Contacted by Outside the Lines, the head of the company that makes the insert said he didn't know what Shoemaker's decision would be.

"I'd be thrilled if he chooses it, and hopefully this will translate to more younger guys starting to wear it," said Matt Meier, SST's founder and CEO.

The 1.7-ounce hard shell is designed to be worn on the pitcher's throwing side, where hurlers are most susceptible to being hit, though guards can be worn on both sides.

The insert Matt Shoemaker will use slides into the cap's sweatband. Shoemaker will use a single guard on his right, throwing side, though inserts are made for both. Safer Sports Technologies

Shoemaker said Astros pitcher Collin McHugh, who has worn the SST head guard for years, first told him about the product. According to Meier, a couple of other major leaguers are considering it, but he's not aware of any who have decided to adopt it yet.

As Outside the Lines reported two years ago, Dan Jennings became the first pitcher known to wear protective headwear after being hit by a liner; he, too, selected the SST insert. But when Jennings struggled with his performance, he elected to stop using the device. Shoemaker is the second pitcher who has been hit to say publicly that he'll wear such protection in games.

The SST guard, which does not have a Kevlar component as it did previously, has not been tested by Major League Baseball. MLB neither mandates any form of protective headwear nor prohibits it, unless it interferes with play or conflicts with licensing agreements. Meier said he's been in touch with the league but has not decided when or whether to submit his product for approval.

The SST insert extends from the front of the hat to behind the ear and provides impact reduction for the vulnerable temple area, which is where Shoemaker got hit, according to Meier.

"We actually make zero guarantees, but we've put the product through a battery of high-velocity tests and believe it reduces the risks of the worst consequences, like skull fractures and brain bleeds," he said.

Shoemaker said one of the products he tried out is the hybrid cap-helmet approved and offered by MLB and the players association. No pitcher has worn that visor-like device in a game.

During spring training workouts, Shoemaker said he alternated daily between the SST guard and the "BCL" ball cap liner of carbon fiber and foam that is produced by former major leaguer Cliff Floyd and his father-in-law, Adam Pauze. Shoemaker said it would have been a good choice, but he has a slight preference for the SST device.

In recent years, about four to six pitchers have been hit in the head by liners each season. Reaction time on a line drive can be about one-third of a second. The Sept. 4 shot that struck Shoemaker left Kyle Seager's bat at an estimated 105 miles per hour.

As a member of the Padres and Mets a few years ago, former MLB lefty Alex Torres drew widespread attention for wearing the bulky MLB/MLBPA-approved isoBLOX foam-padded cap, and a version of it ended up on display in Cooperstown. Two other former major leaguers wore Unequal Technologies' Kevlar-lined Dome cap in 2015.

Pitchers throughout the majors acknowledge that regardless of whether they get hit in the head, they're creatures of habit and are reluctant to pursue anything that might even slightly disrupt their motion, routine or thought process -- no matter what the arguments are for increased safety.

"The sense of not knowing it's there is huge," said Shoemaker. He also said a key indication of his return to normal after the trauma of September is that he's not thinking about what happened -- unless he's asked about it.

"I'm very, very thankful for how everything has turned out and that God's watched over me," he said.