Sizes: This stopper beads about 4mm in diameter, 3.3mm thick, hole: 1.8mm, rubber hole: 0.5mm, 40pc pack. Easy for you to link these round stopper beads with other findings. Function: This stopper bead has a built-in rubber that plays an important role in spacing, positioning and preventing loss. It prevents sliding between adjacent beads, which helps to keep the beads separated. Material: The round spacers beads are made of 202 stainless steel, using safe materials. They will not cause any harm to your skin. Strong and durable, they do not rust or warp easily, have an aesthetic appeal and are comfortable to wear. The surface is glossy and shiny and does not fade easily. Wide Usage:Stopper spacer beads can be used to make various DIY crafts or jewelry making, can be widely used in bracelets, necklaces, earrings, pendants, cell phone decoration, etc. Separating them from other decorations plays a great role in layering beautification. Easy To Use: The stopper beads with silicone sliding beads inside can be used to align multiple necklace or bracelet strands and prevent tangles , and can be worn between two beads or jewellery for layering.