Zincs Alloys materials : It is cast with thick Zincs Alloys materials , which is not easy to rusts and age Reinforced telescopic chain : Reinforce the chain , increase the pulling force , and thicken it and it is not easy to break Single switches : Single to , redness mean to , black mean to open , and practical Thickening materials : The materials is thick and full , the inner cores have a builted-in spring designs , which cushions the stress and is Enduring Spikes designs : Spikes designs is used , which is not easy to bounce and not easy to damage, Manufacturer: Watreketal