The NFL Players Association “tentatively agreed” to let the league take 40 blood samples for HGH tests each week during the season, with a positive result drawing a four-game suspension, according to a memo the union sent players.

A copy of the NFLPA’s email, written in a question-and-answer format, was obtained Tuesday by The Associated Press.

The memo says “a computer program will randomly select” five players apiece from eight teams each week to take the blood tests.

First, though, every player participating in NFL training camps this year will provide a blood sample and information about “height, weight, age, and race/ethnicity” for a “population study” to determine what level of HGH will result in penalties, the union wrote.

The NFLPA’s letter says that if more than 5 percent of all training camp samples are above that threshold, players who fail will have “reasonable cause” testing during the next two seasons — meaning they’ll be subject to additional testing. A player testing positive again during the 2013-14 or 2014-15 seasons will get an eight-game suspension.

Tuesday’s email to players indicates the union has signed off on aspects of the HGH program and says owners and players “will likely finalize soon” the weekly testing.