Seco 18 oz (510 g) Plumb Bob The Seco 18 oz Plumb Bob is designed for increased stability in outdoor and moderate wind conditions. Its heavier weight improves vertical accuracy, making it well suited for more demanding surveying and layout applications. Key Features • Heavier 18 oz weight for improved stability in field conditions • Solid brass construction for long-term durability • Hardened steel point for accurate alignment and marking • Internal storage for spare point