Abstract: A rigid base with an integral post projecting thereabove between its ends has a tubular slideway formed through the post and the bottom of the base. A cylindrical slide is reciprocable in the slideway and has a picker finger secured to its bottom with opposite tapered ends projecting under the adjacent portions of the bottom of the base. A screw is threadedly engaged in a tapped bore in the top of said slide, and has a head on its upper end exteriorly of said post. The head is restrained against axial movement relative to said post. A slot formed vertically through the side of said post slidably receives a pin connected to said slide to prevent rotation of the slide. Said pin also serves as an indicator. A manually engageable handle is formed integrally with said base and said post.