The heads use a Torx drive system

1/4-20 x 7 1/2 Grade 8 Hex Cap Screw Yellow Zinc Plated Domestic USA (600)

1/2-13 x 2 1/2 A325 Type 1 Heavy Hex Bolt Hot Dipped Galvanized (300)

7/16-14 x 2 1/2 L9 Hex Cap Screw Yellow Zinc Plated Domestic USA (50)

Simpson ETBS Wire Hole-Cleaning Brush Extension - Useable Length 8 1/2" (for use with ETBS-TH T-Handle) 1 1/2-6 Socket Cap Screws Alloy The heads use a TorxSimpson's ETBS 8 1 2" extension brush is designed for use with the ETBS TH T Handle to provide deep cleaning to hard to reach places. Its durable, corrosion resistant wire bristles make it ideal for removing scale, rust, and other debris.