From FlyerGuide Wiki

OK Plus Silver: For members who earn 25,000 miles or who take 15 SkyTeam flight segments in one calendar year. Benefits include:

• 25% mileage bonus.
• Business class upgrades when available. (2000 miles deducted for long-haul flights)
• Priority check-in and airport standby.
• 10 kg excess baggage allowance.
• Priority waitlisting and boarding.
• Preferred seating when available.
• Access to ABC lounge at Prague Airport.

OK Plus Gold: For members who earn 50,000 miles or who take 30 SkyTeam flight segments in one calendar year. Benefits include the above listed, plus:

• 50% mileage bonus.
• Access to SkyTeam lounges worldwide including one guest.
• Priority baggage handling.
• 20 kg excess baggage allowance.
• Guaranteed reservations where available.