A. Different of technology and materials, you can check the details of the difference. Techwin Cheap model Shell PC+glass fiber,                                                          Feature: Flame retardant grade V0, high temperature resistant up to 220 Degree pc, plastic， feature：get soft once the temperature is above 150 degrees, Connector copper steel Potting compound Flame-retardant and heat-insulating potting compound no potting compound or just use cement  low-temperature soldering 145°low temperature lead-free soldering tin, 3 times cost. 260°soldering tin, Easily lead to failure of protection and even fire piezoresistor ∅34*34 ∅25， can not meet the standard of lightning protection. R&D capacity Own lab and technology team no Solution of lightning protection OEM and ODM are all available, will give you the best technology solution OEM only, no R&D ability   B. Certification: whether have international certificates or Testing report from CNAS lab. We have UL, TUV, CE, RoHS, ISO9001, ISOD14001, ISO45001, Testing report of IEC61643-11.