Snap On Chrome Flank Drive Plus Combination Spanners. Sizes include 11,12,13,15,17 & 18mm. I’ve taken a close up of the 17mm spanner as its had the most use, the others are a lot better in comparison. Please zoom in and inspect the pictures. This set of combination spanners is made by Snap-on, a well-known brand in the industry. These spanners use the metric system of measurement and have the special Flank Drive Plus design, which provides better grip and reduces the chance of slipping. The chrome finish also adds to their durability and aesthetic appeal. They are perfect for use in garages or for DIY projects.