All listed balusters are available for Stairways Inc wood-based spiral staircases. Recommended for wood spiral stairs in traditional interior settings. Any turned baluster is also acceptable for interior use. All square and round balusters can work in modern/contemporary settings, working well with single spiral staircase designs. Can also be combined using multiple baluster types to create repeating designs. Stairways Inc standard wood species are made from red oak, but any species can be used for different projects. All wood stairs are built in our plants, disassembled, and numbered for shipping. Guaranteed durability and long lifespan.