Uxcell 10 Pcs M4 x 40mm HEX Spacers Nylon Hexagonal Pillar Female-Female Inner Thread 1.Hex Spacers are appropriate for use in low-strength assemblies 2.Made from BSI and RoHS Certified quality Nylon 66. 3.Nylon 66 is suitable where non-conductivity, corrosion resistance, and cost are important considerations 4.Drive system is a hexagon-shape 5.Coarse threads are better for brittle materials, and will assemble and disassemble more quickly than fine threads 6.Ensure a lasting hold for any projec