Major League Baseball begins spring training without an approved choice of protective headgear for pitchers, and it's uncertain whether any product will receive approval in time for the regular season, MLB senior vice president Dan Halem told "Outside the Lines" on Monday.

Halem said baseball officials have spent the offseason considering and testing padded linings for caps, with the hope that by spring training, MLB would be able to approve and present to the players association multiple options for pitchers to try out on a voluntary basis.

San Diego Padres pitcher Chris Young is helped off the field after being struck with a batted ball in May 2008 by Albert Pujols, who stands nearby. Chris Hardy/SD Padres

"We're not going to approve a product unless our experts say it provides adequate protection," Halem said.

So far, said Halem, no new cap design satisfies requirements MLB set for providing head protection against high-speed batted balls. He said proposals from six companies are being considered, but that only two have submitted actual prototypes for MLB to test at a University of Massachusetts-Lowell laboratory.

As ESPN.com reported in December, among the padded linings for caps Halem said MLB is considering is one that features DuPont Kevlar, made by Unequal Technologies, and another that uses an advanced foam "gel-to-shell" product, made by EvoShield. Representatives of both companies told OTL that they have been making adjustments to what was originally submitted based on feedback from MLB.

"It may take multiple iterations," Halem said.

Halem said pitchers would not be violating rules by independently deciding to wear any type of padding -- or even a helmet, although neither MLB nor the manufacturing companies have considered helmets for pitchers. He didn't rule out a lined cap receiving MLB's endorsement and being ready for use by Opening Day, saying, "We'll see if the two companies that are farthest along can complete testing, satisfy our criteria, and then produce fast enough."