High-quality material: The round screw spacer is made of high-quality nylon material, which has good temperature resistance, oil resistance, corrosion resistance, and tear resistance, ensuring a long service life. 14 sizes included: 40 pcs 3x7x3; 20 pcs 3x7x5; 20 pcs 3x7x6; 20 pcs 3x7x8; 20 pcs 3x7x10; 20 pcs 3x7x12; 20 pcs 3x7x15; 40 pcs 4x7x3; 20 pcs 4x7x5; 20 pcs 4x7x6; 20 pcs 4x7x8; 20 pcs 4x7x10; 20 pcs 4x7x12; 20 pcs 4x7x15. Total of 320 pieces, suitable for most screws. These spacers are rust-resistant, stable, and insulating. Simply measure the required length for the screws and select the appropriate spacer that is shorter than the screw to allow the board to sit flush with the wall. Wide range of applications: Suitable for micro-motors, automobile manufacturing parts, electronic products, instruments, machinery, stationery, automation equipment, toys, and hardware accessories. Commonly used to protect LEDs on circuit boards. Material: Nylon Color: Black Package Contents: 160 x M3 isolation columns (40 x 3mm, 20 each of 5mm, 6mm, 8mm, 10mm, 12mm, 15mm) 160 x M4 isolation columns (40 x 3mm, 20 each of 5mm, 6mm, 8mm, 10mm, 12mm, 15mm) Note: Lighting effects and monitor settings may cause slight color variations between the image and the actual item. Measurement may vary by 1-3 cm.