Size 5 Glass Cupping Cups As used by Traditional Chinese Medicine Practitioners, Massage Therapists, Cupping Therapists and Hijama Practitioners. – Inner Diameter: 3.5cm Usage DURABLE, EASY TO USE, MULTI-PURPOSE A good quality thick glass, the cup has a flat top for fire cupping techniques, the flat top also provides a stable base to prevent the cup from rolling on a flat surface. The glasses are made of fireproof and safe glass. They are all easily disinfected. The advantage over plastic lenses is that they do not get dull or cracked even after many applications.