From the Johnny's Selected Seeds website:
Includes a Jang JP-1 Seeder and a collection of seed rollers (LJ-12, X-24, F-24, XY-24) for seeding a wide variety of vegetables including beets, carrots, lettuce, onions, spinach, radish, and more. We selected these rollers based on rigorous trials at the Johnny's Research Farm.
Includes:
• Jang JP-1 Seeder (#7319)
• LJ-12: For small-seeded beets (raw seed), carrots (#13 pelleted), lettuce (#13 pelleted), onions (#13 pelleted), small-seeded spinach, basil (#13 pelleted)
• X-24: For broccoli, Brussels sprouts, cabbage, cauliflower, greens, onions (raw seed), dill
• F-24: For small-seeded spinach, radish
• XY-24: For carrots (raw seed), lettuce (raw seed)
Here's a video describing how to use the seeder: