Retractable utility knife

A retractable utility knife comprising:

• a first liner comprising a control track extending along the first liner, the control track comprising a first notch having a first depth at a first end of the control track and a second notch having a second depth spaced apart from the first notch along the control track;
• a carrier arranged to receive a replaceable blade, the carrier slidable relative to the liner between a first configuration and a second configuration, the carrier comprising a spring arm and a control pin, the control pin extending into the control track;
• and
• a first scale and a second scale, the first and second scale together encompassing an interior volume, wherein the first liner and the carrier are disposed within the interior volume;
• wherein the spring arm is arranged to bias the control pin into the first notch in the first configuration, and to bias the control pin into the second notch in the second configuration,
• wherein the control track comprises a third notch disposed along the control track spaced from the first notch and the second notch, the third notch having a third depth greater than the first depth and the second depth, and
• wherein the third notch is disposed between the first notch and the second notch longitudinally along the control track, and wherein the spring arm is arranged to bias the control pin into the third notch in a third configuration, different from the first configuration and the second configuration.