Base 204 – Fir Call For Quote $2.15 Interior Base Fir, 5/8″ x 3-1/2″ View Product Catalog Base 204 - Fir quantity Add to list Want a discount? Become a member. SKU: 204-F Category: Mouldings Description Description Mid Century Modern clamshell base. F204 – Fir, 5/8″ x 3-1/2″ available in random lengths.