High purity corundum tubeStructure model type: protective tube has closed form, general form two. Structure type: protective tube has closed form, general form two. Structure type: protective tube has closed form, general form two. Structure type: protective tube has closed form, general form two. A insulation tube be round, elliptical, be divided into single hole, double hole, and porous. A insulation tube be round, elliptical, and divided into single hole, double hole, and porous. A insulation tube be round, elliptical, and divided into single hole, double hole, and porous. Kɔ̈k peei, tɛ̈n tɛ̈n tɛ̈n tɛ̈n tɛ̈n tɛ̈n tɛ̈n tɛ̈n tɛ̈n tɛ̈n