Rulers often slip and slide as you're using them, resulting in uneven, crooked lines. This ruler features non-slip colored bumps so you don't have to worry about your ruler shifting out of place! You can use both the back and front of this non-slip ruler. When using the front, press down on the colored bumps to avoid slippage. When using the back, press down anywhere except the bumps. Measurement markings are engraved into the ruler so they won't fade away.