Tianjin Sijia Technology Co., Ltd.

Tianjin Sijia Technology Co., Ltd. Was established in 2015 and is located in Tianjin. It specializes in the production and research and development of waterproof phone cases, swimming bucket bags, beach shoes, wading shoes, water shoes, and non-inflatable swimming rings and other water sports equipment. It has successively served central state-owned enterprises in the cultural and tourism industry, as well as chain water parks and hot springs such as Happy Valley Maya Water Park, Huaqiang Fangte, Chimelong in Guangzhou, Atlantis in Hainan, Poseidon in Harbin, and Yinzijia in Zhengzhou. It has long-term strategic cooperation with leading domestic brands such as Li-Ning, Xtep, Peak, Jordan, Hongxing Erke, Little Yellow Duck, Yimei Shan, Sanqi, and Kaidilong, providing better product experience and service. Since 2019, Sijia has entered the international market through a three-stage process of "certification first, then samples, and then bulk production". Currently, export business accounts for 45% of the company's production capacity, with direct customers covering 42 countries and indirect access to over 280 water parks and retail terminals worldwide.

The company has a 3, 000 square meter manufacturing base with an annual production capacity of 6 million waterproof bags, 1.5 million pairs of wading shoes, and 200, 000 non-inflatable swimming rings. It is a high-tech enterprise integrating research and development, design, innovation, and environmental protection. The cooperation forms include OEM, ODM, and OBM. For over 10 years, it has been dedicated to doing one thing - keeping water out of the equipment. With molecular-level technology, it redefines water-friendly equipment, providing an "extreme comfort and safety" experience for every water encounter. It is committed to becoming the leader in water scene protection equipment in China and a new international benchmark.

All raw materials are dual-certified by international SGS and EMTEK for environmental compliance, with 100 % traceability from pellet to product.

Our campus operates intelligent production lines anchored to a self-built, aerospace-grade technology platform:

Frequency-molecular fusion: Phase-locked at 27.12 MHz, delivers full-penetration, zero-weld seams; Waterproof pouches certified to IPX8 immersion.

Nano-crystalline injection: Mold-cavity tolerance held to 0.005 mm for micron-level accuracy.

Quantum-ultrasonic welding: 40 kHz variable frequency, bond strength ≥ 95 % of parent material, zero-adhesive and greener.

One-shot injection molding at 160-170 °C merges upper and outsole into a seamless, stitch-free unit-eliminating traditional de-lamination risk.

Adhesion + seam-sealed tape survives -20 °C flex tests without cracking.

One-piece knitted Flyknit uses 3D bio-mimetic weaving to mirror the foot's anatomy like a second skin while cutting weight by 35 %.

Warp-knitted Jacquard employs 0.8-1.2 mm precision vents to deliver 600-900 mm s¹ airflow (ASTM) for marathon-level breathability, yet retains ≥ 15 N mm¹ lateral support for zero distortion on hard cuts.

Fused into a single system, these black-grade technologies create submarine-grade sealing plus ultra-precision comfort-redefining the waterproof footwear experience.