The smaller sizes in our Baby Range (S, M) have a soft non-slip suede sole to encourage optimum foot development at these early stages of foot development. They are not designed for walkers however can of course be worn outside to keep little feet warm and cosy. The larger sizes (L, XL) have a flexible, rubber sole which provide a more robust design for babies who are standing or cruising. However, these styles are designed for mostly inside use, with a small amount of outdoor use tolerated. They are not designed to get dirty or wet. If you are looking for a 1st Walker style that can tolerate outdoor use, we recommend our 1st Walker Range.