🔩 1. The 0.65 m length isn’t arbitrary

A crank handle around 650 mm gives the best leverage for manual side‑vent systems on small and mid‑size polytunnels. Shorter handles (<50 cm) make the gearbox harder to turn under tension, while longer ones (>80 cm) can strain the gearbox shaft. So your product sits right in the “optimal torque” range.

🌬️ 2. Side‑vent gearboxes are one of the most reliable ways to control tunnel climate

Growers using crank‑operated side vents typically see:

• Lower humidity spikes
• Reduced fungal pressure (especially botrytis)
• More stable temperatures
• This makes the crank handle indirectly responsible for healthier crops
• 🛠️ 3. Handles are often replaced more than gearboxes.

In real‑world use, the handle is the part that gets knocked, bent, or weathered first — not the gearbox. Offering it as a standalone accessory is smart because:

• It’s a common replacement item
• It’s a low‑cost add‑on
• It encourages customers to maintain their ventilation system rather than ignore it

🌧️ 4. Polytunnel environments are harsh on metal components

Even treated steel or aluminium handles face:

• Condensation
• Soil moisture
• Fertiliser salts
• UV exposure
• Daily mechanical stress

So emphasising durability and regular‑use suitability is absolutely on‑point for customer expectations.

🧱 5. A crank handle improves usability for older growers

Many customers choose manual side vents because they’re simple and reliable — but they can be stiff. A well‑designed crank handle:

• Reduces wrist strain
• Makes daily venting easier
• Helps customers with limited mobility continue gardening comfortably.