Simpson HDU4-SDS2.5 10-15/16" Predeflected Holdown w/Screws. Simpson Strong-Tie HDU Holdowns are pre-deflected to virtually eliminate deflection under load due to material stretch. The Strong-Tie HDU4-SDS2.5 pre-deflected holdown is installed with Simpson Strong-Drive SDS heavy duty connector screws which are included with the holdown. Call Rich (908) eight seven five seven seven five nine. $20 each I have approximately 90.