The Altra 166 Outsert 400 Spine is a precision-end component designed for archers using Altra Arrows 166 shafts. Built for shooters who demand repeatable flight and easy tuning, it adds a durable, vibration-damping end to your arrow.

• Compatibility: Fits Altra Arrows 166 Shafts.
• Material: Machined from 7075-T6 aluminum for lasting durability.
• End Encapsulation: Outsert encapsulates arrow end to 0.43 inches.
• Insert Depth: Secure insert depth of 0.875 inches.
• Vibration Reduction: Pre-installed rubber O-rings reduce vibration and improve concentricity.
• Pack Size: 12 pieces per package (1 dozen).
• Spine Options: Available in 250, 300, 350, and 400 spine.
• Total Weight: 50 gn total weight.
• Insert Weights: Accepts micro FMS insert weights.
• Performance Benefit: Enhances downrange accuracy and precision.

The 1-dozen package makes it convenient to maintain consistency across multiple arrows or practice rounds. With four spine options, you can fine-tune stiffness to match your bow and draw length, while the O-rings and end encapsulation work together to minimize vibration and keep arrows flying true. Use with micro weights to dial in wind drift and distance, delivering tighter groups on targets and improved confidence at varying shooting conditions.