I recently purchased these zinc plated CARRIAGE washers for an industrial project and they did not disappoint. My analysis of this product showed that they are extremely durable and resistant to corrosion. The square neck shape allows for easy installation and prevents the bolt from turning, providing a secure hold. The only downside is that they are a bit pricier than other options on the market, but the added quality and longevity make up for it in the long run. Overall, I highly recommend these bolts for any industrial or scientific use..