The figures are a mix of 20mm plastics and metal models.
The Finns are primarily the fantastic Eureka Miniatures and Fantassin lines with some Lancashire Games, Foundry and Reviresco figures thrown in. They're augmented by some figures converted from Caesar and Revell, Pegasus Hobbies and Esci Germans.
The Soviets are primarily Lancashire Games and old IT Miniatures WWI Russians (at the time of purchase also owned by Lancashire Games). In addition there are Fantassin, Revell, Nexus/Atlantic, Popeda, Warrior, Platoon 20, Skytrex, Foundry and even Airfix figures in there.
The mix of figures gives the troops a slightly shabby look which I find very appropriate for the Winter War. Sadly many of the figures are quite old and would benefit from repainting using modern techniques. Others are new and still being finished and will hopefully look a bit better at some point.