To help eliminate problems during mounting TVs to wall units Meets VESA Standards (Video Electronics Standards Association) 304 Stainless Steel - No Rust Ever Easy install with Phillips head screwdriver Bolt Size for TVs & Monitors VESA under than 200 measures 200 mm x 200 mm (approx. 8inchx 8inch) Uses M4 (Small) screws VESA 200 measures 200 mm x 200 mm (approx. 8inchx 8inch) Uses M6 (Medium) screws VESA 400 measures 400 mm x 400 mm (approx. 16inchx 16inch) Uses M8 (Large) screws To help eliminate problems during mounting TVs to wall units, an industry-wide group was formed named VESA (Video Electronics Standards Association).
Most TV manufacturers comply with the standards established by VESA. If you look at the back of your TV you will notice that the screws holes are in a perfect square pattern.

When you measure the distance between holes they should be as follows:
VESA 75 measures 75 mm x 75 mm (approx. 3inch x 3inch)
Uses M4 (Small) screws

VESA 100 measures 100 mm x 100 mm (approx. 4inch x 4inch)
Uses M4 (Small) screws

VESA 100/200 measures 100 mm x 200 mm (approx. 4inch x 8inch)
Uses M4 (Small) screws

VESA 200 measures 200 mm x 200 mm (approx. 8inchx 8inch)
Uses M6 (Medium) screws

VESA 400 measures 400 mm x 400 mm (approx. 16inchx 16inch)
Uses M8 (Large) screws

Package included:
4Pcs M4x10mm screws with 4Pcs M4 washers
4Pcs M6x20mm screws with 4Pcs M6 washers
4Pcs M8x20mm screws with 4Pcs M8 washers