The Original Expansion Bolt for Structural Steel. Suitable for hollow sections, tubes and where access is available from one side only. The only expansion bolt to have full Seismic approval for resisting wind loads and seismic loads. For corrosion protection the Hollo-Bolt® comes with additional JS500 protection as standard. Sizes M16 and M20 have a patented High Clamping Force (HCF) mechanism for optimised clamping force. Speedy installation with standard tools. Awarded the Design Council’s Millennium Product status for innovation in the year 2000.