1) What is the difference between Sub45 - Sub 90 - Sub180?

The pack names reflect their intended running duration:

Sub45 - Built for short runs (up to ~45 minutes, the majority of runs). It’s the smallest, slimmest, and lightest stretch pack. Designed to feel almost invisible, it carries only the essentials: phone, keys, gels, and other small items. It does not have a built-in hydration system, though small flasks can fit in the pockets.

Sub90 - Same footprint as Sub45 but 1 cm thicker to accommodate a 500 ml slim bladder in a thermo-pocket. It features a hidden tubing system, a full stretch structure and a larger back pocket for longer items.

Sub180 - The largest pack, built for long runs or minimalist day outings. Instead of stretch points, it uses triangulation and anchor points to stabilize heavier loads. It offers more frontal access with a quad pocket, an expandable back, and a larger 1.1L bladder.

👉 Quick guide:

• Sub45 → everyday runs under 45 minutes.

• Sub90 → medium runs up to 90 minutes, with hydration built in.

• Sub180 → long runs or light adventure days, up to 180 minutes.

2) Which size fits me?

• Sub45 & Sub90 come in 2 sizes: XS–S and M–L–XL.

  Measure 2 inches below your pectoral muscle/band line. If between sizes, consider seasonal layering (jacket vs. T-shirt).

  • XS–S: 26–31 in (67–78 cm)

  • M–L–XL: 31–40 in (78–102 cm)

   

• Sub180 comes in one adjustable size: XS–XL (24–48 in / 60–121.5 cm).
  Adjust order: sides → bottom chest strap → upper chest strap.

3) How do I adjust my FITLY?

Proper adjustment takes just 30 seconds and makes a huge difference in comfort.

• Sub45 / Sub90 – Position thoracic belt ~2 in below pectorals. If too loose, items shift; too tight, you’ll feel restricted. Aim for snug, not tight.

• Sub180 – Adjust sides first, then bottom chest strap, then upper chest strap.

4) IMPORTANT: maintain your zippers.

Your pack’s zippers endure a lot on the trail. With maintenance, they’ll last for decades; without it, they can lock up.  Read the blog that explains how to care for your zippers.  You’ll be thankful you did!

5) How do I wash my FITLY?

• Hand wash with mild soap and lukewarm water.

• Rinse in the shower after runs, then hang upside down to dry.

• Avoid washing machines (they strip the water-resistant coating).

• To speed drying, stuff pockets with paper towels.

6) How does the hydration system work?

• Always rinse new flasks/bladders before first use. If taste persists, soak in baking soda solution for 15 minutes.

• Sub90 – Includes a slim 500 ml bladder. The vacuum suction system requires a tight seal. Screw cap securely, use olive oil on threads if needed, and check the flow stopper (twist or pull to open).

• Sub180 – Comes with a larger bladder. Thread the tube through shoulder straps, leaving ~1 cm of clearance at the bottom to avoid blockage. Seal tightly.

💡 Tip: Dry flasks upside down with a spoon inside to promote airflow.

7) I try to drink and nothing comes out, what am I doing wrong?

• Check the flow stop — it may be closed.

• Ensure the tube isn’t inserted too far inside the flask (TPU can block flow).. 

8) Where can I store which flasks?

• F1 – Front pockets (except Sub90 XS–S when full).

• F2, F3, F4, F5L – Back pockets of any FITLY + upper front of Sub180.

• F5 / F5B – Included with Sub90; fit only its thermo-pocket (not Sub45).

• F11 / F11B – Included with Sub180; fit its thermo-pocket only (not Sub45/Sub90).

• F17 / F17B – Standalone bladders; compatible with Sub180.

All flasks share the same tubing system. Note: Sub45 is designed for light loads — overpacking may cause bounce.