unitracks are nearly all perfect, but you'll skate on thin ice at R216 or tighter. These work well for 4-6-2s at the largest

These are solidly made. Train runs smoothly on these.

Wanted to make a small layout and needed sub 24 diameter. These fit the bill perfectly and the 6 axle loco handles the Kato curved 9.75 track segments with no issues. While