... other word.3,Gear shaft:The material is 45#steel,with furface carburization treatment for high strength and wear-resistance. ... 4,Spring:Adopts quality spring steel,with less than 1mm shortening afer 300,000times squeezing.At door ... 1 Two stanges speed controlled range:180 degree -15 degree,latch speed:15 degree -0 degree. 2 90 degree hold-open fuction:door can keep standstill ...