High-quality material: The round screw spacer is made of high-quality nylon, offering good temperature resistance, oil resistance, corrosion resistance, and tear resistance for 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 and select a spacer shorter than the screw to allow the board to sit flush against the wall. Wide range of applications: ideal for use in micro-motors, automobile parts, electronic products, instruments, machinery, office supplies, 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 5/6/8/10/12/15mm); 160 x M4 isolation columns (40 x 3mm, 20 each of 5/6/8/10/12/15mm). Package includes only the items listed. Note: Lighting and display differences may cause slight color variations between the image and actual item. Measurement tolerance: ±1-3 cm.