Abstract: Safety cutting blades and utility knives having such blades are presented. Safety cutting blades include safety features that protect users from contacting a cutting edge. Preferred blades comprise a stem and a cross bar that orthogonally intersects with the stem. One or more cutting edges can be disposed within a notch made into an edge of the blade. Safety features can include safety guards located at one or more ends of the cross bar where the safety guards cooperate with the stem of the blade to form the notches. The notches can be sized and dimensioned to reduce a risk of a body part from contacting a cutting edge.

Abstract: A utility knife has a counter-reciprocating blade and blade guard. Preferred utility knifes have an internal mechanism comprising several components that are advantageously coupled via one or more pivot points. Though an appropriate arrangement of pivot points, both stationary pivot points and translating pivot points, the blade and guard counter-reciprocate such that forced retraction of the guard results in forced extension of the blade. While the internal mechanism is in a locked position, the guard locked. Actuation of a trigger can unlock the internal mechanism, which releases the blade guard. Preferably a single actuation of the trigger provides for a single use of the knife.

Abstract: A tool holder is presented. Preferred tool holders include a holster for securely holding a tool. A tool bit can be operationally coupled to the holster so that the holster-tool bit assembly forms a complete tool, where the holster can function as a handle of the tool bit. The tool bit can be of the same type, or of a different type than that of the held tool. Some embodiments include tool locks that securely hold the tool within the holster when the holster is used to operate the tool bit.

Abstract: A tool system is presented. The tool system includes a tool body sized and dimensioned to fit comfortably in a human hand, and includes a plurality of interchangeable tool cartridges. Some of the tool cartridges include a tool bit cover capable of remaining in a closed, locked position sheathing a tool bit. Once installed, the tool bit cover can be unlocked via actuation of a trigger disposed on the body of the tool or on the cartridge. Preferably, the tool bit cover unsheathes the underlying tool bit due to pressure or force of a work surface.