this product has good electrical insulation properties, arc resistance and arc extinguishing properties.There are three types of products:                                        
1.They are all vulcanized fibre tube.                                
2.the outer layer is kraft paper, the inner layer is     vulcanized fibre tube. It is a composite material.                
3.the outer layer is fiberglass,the inner layer is vulcanized fiber tube. It is a composite material.  
this product applies to:                                           
"K" type high-voltage fuse link                                   
"T" type high-voltage fuse link                                   
"F" type high-voltage fuse link                        
Capacitor dedicated fuse link