... 2,High quanlity; 3,Iron core, steel core, PE core, PE core is better The core material can be iron, steel and ... even reaches 100 meters.In this picture, the core is made of steel.It is good,but ... this picture,the core is made of PE.This PE core is better than steel core.This core is the ... best.In this picture,the steel core,the iron core and the PE core ...