Ultrasonic welded seams — no needle holes

Conventional bag construction stitches panels together, leaving tiny needle holes at every stitch point through which water and warm air can slowly enter. Ultrasonic welding fuses TPU-coated nylon panels together using high-frequency vibration — no needles, no thread, no holes in the seam line. The result is a seam that is genuinely airtight and waterproof rather than just water-resistant. For a cooler where thermal retention depends on the seal quality, this construction method matters.

Airtight zipper — keeps cold in

An airtight zipper maintains the cold compartment seal when closed. Standard zippers allow air exchange at the teeth — acceptable for a regular bag, but counter to the purpose of a cooler where keeping cold air inside is the goal. The airtight zipper works with the welded seams to make the cooler function as a sealed thermal environment rather than a loosely insulated bag.

FDA-compliant, BPA-free food liner

The internal liner meets FDA food-contact standards — it's safe for direct contact with raw food, produce, loose groceries, drinks, and anything else that shouldn't touch a generic bag interior. BPA-free construction means no bisphenol A in the liner material. For a cooler used to carry groceries directly from the store, the food-safety specification of the liner is as relevant as the thermal performance.

TPU-coated nylon — waterproof inside and out

Thermoplastic polyurethane (TPU) coating bonds to the nylon fabric and makes it impermeable to water and most liquids. The coating is applied to both interior and exterior surfaces — road spray, rain, and condensation from cold contents stay where they belong. The EVA base layer provides additional structure and insulation at the bottom where contents rest. Together, the materials make the cooler cleanable with a wipe or rinse rather than requiring hand washing.

On-bike and off-bike use

The WeatherTop Cooler mounts to compatible Tern racks via built-in quick-release buckle straps and detaches in seconds. Off the bike, it functions as a standalone soft cooler — handles allow it to be carried to a picnic, beach, or campsite. The same thermal performance that keeps groceries cold during a 20-minute bike ride keeps drinks cold for hours in a static setting. The two use cases share one bag without compromise or conversion.

Wraparound reflective decals — visibility when loaded

When the WeatherTop Cooler is mounted on a rear rack, it is the largest object at the back of the bike — and the most visible to following traffic. Reflective decals wrap around the cooler's exterior, returning light from vehicle headlights at night. The wraparound coverage means the cooler is reflective from any rearward angle, not just directly behind.