The coordinates point to a 0,3 l regular-sized cache-box somewhere in Luukkaa outdoor recreation area. Coordinates of the next stop are written on its lid. Second stop is similar and contains coordinates for the final cache, which is a 0,8 l box covered with black tape.
First box is under a root and cannot be found when there's snow on the ground. At final cache site you don't need to remove anything to reach the box.
There is a parking lot very close to the starting point. Bus line 345 has its stop near the starting point at Kaitalampi.
Total walking distance is about 4 km (one way).
Don't delete final coordinates from your GPSr. You'll need those with Pentagram-5. In logbook there's also crucial clue for Pentagram-4.
Links to other caches in this series:
Pentagram-1
Pentagram-3
Pentagram-4
Pentagram-5