The arrow that made Terra Firma's name — over a decade of proven hunts behind it.
The Fortis 4mm is Terra Firma's original shaft, built for bowhunters who need speed, precision, and toughness in one package. The slim 4mm micro-diameter profile cuts through wind and reduces drag, while the dense carbon build handles the impact of hitting bone without flinching.
Specs — 500 Spine:
7.6 GPI (grains per inch)
5.77mm / .227" outer diameter
4mm / .166" inner diameter — compatible with all .166 nocks and components
32" shaft length — ready to cut down to your draw
.001" straightness tolerance — every arrow laser checked and sorted
+/- 1gn weight tolerance across the dozen
What's in the pack:
12x Fortis fletched arrows — 4x 3" vanes, strong right helical
12x Fortis 60gn alloy outserts, spine matched (must be glued in prior to use)
12x TF .166 nocks — short profile, durable
Paired with the 60gn alloy outsert system, the Fortis holds a high FOC for a heavyweight arrow — meaning powerful, consistent flight and hits that punch through even on the tougher shots. Whether you're set up on deer or working boar in thick scrub, this is a dozen you can trust to fly true every time.
