More than 10,000 former NFL players have already registered to receive benefits from a settlement of a controversial class-action lawsuit against the league over concussion-related injuries.

Registration opened for the estimated 20,000 retired football players on Feb. 6 with a highly publicized event held by the federal court and lawyers encouraging players to sign up by the Aug. 7 deadline.

“We are encouraged by the immediate and enthusiastic participation from retired NFL players so early in the registration period,” Christopher Seeger, co-lead counsel for the players, said in a statement. “Although registration will remain open for several more months, we urge all class members not to delay and immediately sign up today.”

The settlement put an end to a contentious legal battle between players and the NFL over claims that the league was aware of dangers surrounding repeated head injuries on the field but did nothing to prevent the issues until recently. Under the settlement, the league admitted no fault and agreed to pay an estimated $1 billion to compensate players.

Retired players who are diagnosed with a set list of neurological diseases typically brought about by head trauma will receive financial compensation from the league. Degenerative diseases covered include chronic traumatic encephalopathy (CTE), amyotrophic lateral sclerosis (ALS), dementia, Alzheimer’s disease and others.

A maximum award of $5 million will go to players suffering from the most severe diseases. An average of $190,000 is estimated to go to about 6,000 who could be eligible to receive financial compensation.

Number of NFL Players Signing Up Lower Than Expected

While roughly half of the former players covered under the settlement have already signed up, some were expecting more in the first month.

“I find it interesting that only 50 percent have registered,” Pittsburgh attorney Jason Luckasevic told the Tribune-Review. “That tells you that a lot of guys are apathetic or unable to realize that they need to do something.”

Along with the unusual conference in February to publicize the registration process, lawyers and players have been encouraging eligible players to sign up. However, some players are resistant to registering.

“I’ve got a number of recently retired players saying, ‘I’m fine, I don’t need this program,’” Seeger told Newsworks.

Symptoms of degenerative brain diseases can take years to develop. But, if a player does not sign up before the deadline in August, he will not be able to receive benefits if he is diagnosed with a disease in the future.

“It may take 10 or 20 years for the effects to come into play,” said Seeger. “There are guys being diagnosed in their 40s, 50s and 60s with dementia, Alzheimer’s,  ALS, Parkinson’s — the compensible injuries in the settlement.”

Even players who appear healthy will receive benefits under the settlement. Players will be provided free brain injury testing to see whether they suffer from a neurocognitive disease. This will help gather valuable information about the brain in former football players.

“We need every retired player tested,” Seeger said in February. “That is critical. We can have test results that we can compare 10, 20 years down the road if there is, unfortunately, a neurocognitive decline. Everybody that is entitled to compensation will get it.”

Settlement Opposed by Some Players for Not Doing Enough

While the settlement has been hailed by the league and many players as an important agreement, not everyone is satisfied with the terms.

Prior to the agreement being finalized, a group of players tried to get the settlement overturned because the terms did not adequately cover CTE. The degenerative brain disease is only diagnosed after death and only those who have been diagnosed with CTE after April 22, 2015, are eligible to receive benefits for their family.

The challenge made it to the U.S. Court of Appeals, but the settlement was upheld by Third Circuit Judge Thomas L. Ambro, who said it was a fair agreement.

“This settlement will provide nearly $1 billion in value to the class of retired players,” the judge wrote last year. “It is a testament to the players, researchers, and advocates who have worked to expose the true human costs of a sport so many love. Though not perfect, it is fair.”

Some players like Tony Dorsett have opted out of the settlement process in order to pursue their own lawsuits against the NFL. The league may still be forced to trial.