anti-freezing Solar keymark, ccc, ce, ISO9001 stable performance& good quality specification:bracket: aluminum alloyvacuum tube: three-target tubethe number of tube: 10,12,15,20,30,36daily efficiency: ≥55%(≥42% in winter)hail resistance: 25mmcertificates: ccc, ce, solar keymark, ISO9001packing: eport carton solar collector