IIRC it is four games for the PED, another two for a masking agent on the first offense.
Second offense gets eight games, third offense is 16 games.
As of this year it's now 6 games. Masking + a positive takes it to 8.
Page 9
Step One: The first time a Player violates this Policy by testing positive for a Prohibited Substance; attempting to substitute, dilute or adulterate a specimen; or manipulating a test result, he will be suspended without pay pursuant to the following schedule:
Positive Test Result for Stimulant, Diuretic or Masking Agent -- two regular and/or postseason games.
Positive Test Result for Anabolic Agent -- six regular and/or postseason games.
Positive Test Result for Prohibited Substance plus Diuretic or Masking Agent/Attempt to Substitute, Dilute or Adulterate Specimen/Attempt to Manipulate Test Result/Violation of Section 5 -- eight regular and/or postseason games
Second offense is 16 games
Step Two: The second time a Player violates this Policy by testing positive for an Anabolic Agent; attempting to substitute, dilute or adulterate a specimen; manipulating a test result; or by violation of Section 5,
he will be suspended without pay for sixteen regular and/or postseason games.5 The second time a Player violates this Policy by testing positive for a Stimulant, Diuretic or Masking Agent, he will be suspended without pay for five regular and/or postseason games.
Third offense is now at least two seasons and needing commissioner's approval to return.
Step Three: The third time a Player violates the Policy by testing positive for a Prohibited Substance; attempting to substitute, dilute or adulterate a specimen; manipulating a test result; or by violation of Section 5,
he will be banished from the NFL for a period of at least two seasons, subject to any appeal. Such a Player may petition the Commissioner for reinstatement after 24 months. Reinstatement, and any terms and conditions thereof, shall be matters solely within the Commissioner’s sound discretion.