An organizer for holding surgical instruments comprising: a tray having an upper surface; a plurality of indentations in the tray forming instrument wells (120, 122, 124, 126, 128, 130, 132, 134) having a shape corresponding to the outer shape of instruments; each instrument well (120, 122, 124, 126, 128, 130, 132, 134) configured to have a depth corresponding to the height of a stack of a predetermined number of such instruments, at least one instrument well (120, 122, 124, 126, 128, 130, 132, 134) being deeper than at least one other instrument well (120, 122, 124, 126, 128, 130, 132, 134); characterized in that the organizer further comprising at least a first locking bar (190, 192) at the upper surface of the tray adjacent a first instrument well and mounted for movement between a first position covering a portion of the first instrument well to a second position away from the first instrument well, whereby the first locking bar (190, 192) in the first position blocking the removal and addition of a tool out of or into the first instrument well and whereby the first locking bar (190, 192) in the second position allowing the removal and addition of a tool out of or into the first instrument well, wherein the first locking bar (190, 192) is pivotably mounted on a pin, the first locking bar (190, 192) having a short section extending from the pin and a longer section opposite the short section, the pin acting as a fulcrum and projecting the short section of the first locking bar (190, 192) above the pin when the first locking bar (190, 192) is returned to first position and its corresponding instrument well (120, 122, 124, 126, 128, 130, 132, 134) contains fewer than the predetermined number of a particular tool. a tray having an upper surface; a plurality of indentations in the tray forming instrument wells (120, 122, 124, 126, 128, 130, 132, 134) having a shape corresponding to the outer shape of instruments; each instrument well (120, 122, 124, 126, 128, 130, 132, 134) configured to have a depth corresponding to the height of a stack of a predetermined number of such instruments, at least one instrument well (120, 122, 124, 126, 128, 130, 132, 134) being deeper than at least one other instrument well (120, 122, 124, 126, 128, 130, 132, 134); characterized in that the organizer further comprising at least a first locking bar (190, 192) at the upper surface of the tray adjacent a first instrument well and mounted for movement between a first position covering a portion of the first instrument well to a second position away from the first instrument well, whereby the first locking bar (190, 192) in the first position blocking the removal and addition of a tool out of or into the first instrument well and whereby the first locking bar (190, 192) in the second position allowing the removal and addition of a tool out of or into the first instrument well, wherein the first locking bar (190, 192) is pivotably mounted on a pin, the first locking bar (190, 192) having a short section extending from the pin and a longer section opposite the short section, the pin acting as a fulcrum and projecting the short section of the first locking bar (190, 192) above the pin when the first locking bar (190, 192) is returned to first position and its corresponding instrument well (120, 122, 124, 126, 128, 130, 132, 134) contains fewer than the predetermined number of a particular tool.