Abstract: Apparatus for locking concentric components and alignment with one another generally includes a syringe sheath having a cylindrical wall between a bottom and an open top. A syringe body includes a bottom thereabout for sliding engagement with a syringe sheath inner surface and cleats formed in the syringe body wall in an opposing relationship are guided in two channels formed in the syringe sheath wall. Each of the cleats includes one end attached to the syringe body wall, a free end and a body portion disposed parallel to the channels. The free ends are spaced apart from the syringe body wall and engagement of the cleats with shoulders limits insertion of the syringe body into the syringe sheath. Placement of the cleats prevents tilting of the syringe body from releasing the cleats from corresponding shoulders.

Abstract: Apparatus for retaining concentric parts within one another and enabling limited axial movement therebetween, includes an inner component having a shoulder disposed in an external perimeter thereof and an outer tubular component having a wall and an open end for receiving the inner component and an inner surface for abutting the shoulder and enabling a sliding interface therebetween. A retaining tab is provided and disposed in the wall proximate the open end for depression of a free end toward the wall and a slot formed in the wall beneath the tab enables the free end to be forced therepast for retaining the free end inside the wall for engagement with the shoulder, thus preventing separation of the inner component from the outer component.