form the rebar is preferably installed criss crossed on 2 foot centers approximately 2 inches above the sand bed for a 4 inch thick slab also to provide anchored eyelet inserts for lifting the slab a combination rebar and eyelet insert chair 30 may be placed adjacent the four corners of the slab as best shown in fig1 11 and 12 the chair 30 comprises a vertical internally threaded stem 31 having depending hook arms 32 and 33 which serve as a support for rebars 34 and 35 in the preferred arrangement four chairs 30 are used for a slab each chair being positioned within the form area equidistant from each corner of the form spaced inwardly approximately 2 feet from the edge of the form for a 4 inch thick concrete slab the chairs 30 are designed so that the hook arms 32 and 33 hold the rebar 2 inches above the sand base when the chairs and rebar have been installed a suitable concrete mixture of desired color and texture is poured into the form and the cement surface is floated and leveled prior to the pour a protective bolt 36 is screwed into each of the threaded stems to prevent their filling with concrete as shown in fig1 the.