generally rectangular cross section and a generally cylindrical cylinder 120 that has a generally cylindrical plug receiving passage 125 formed therethrough for receiving and journaling the plug 110 for smooth rotation therein and a generally cylindrical thin metal retaining sleeve 130 for snugly surrounding the perimeter of tumbler receiving portions of the cylinder 120 when assembled as depicted in fig2 the plug 110 the cylinder 120 and the sleeve 130 extend coaxially about a center axis 111 that extends centrally through the keyway 115 referring to fig1 9 and 10 three sets of tumbler bottom pins 150 160 170 three sets of tumbler driver pins 250 260 270 and three sets of springs 350 360 370 are provided for insertion into three sets of aligned holes 450 550 see fig2 460 560 see fig9 and 470 570 see fig1 that are formed in the plug and cylinder 110 120 respectively as is depicted variously in fig2 and 10 inner end regions 152 162 172 of the bottom pins 150 160 170 are rounded and are extensible 1 into concave recesses 652 formed in an edge surface 650 of a 34 suitably configured 34 key 600 see fig2 2 into concave recesses 662 formed in a flat side surface 660 of the key 600 see fig9 and 3 into concave recesses 672 formed in an opposed flat side surface 670 of the key 600 see fig1 respectively a 34 suitable configuration 34 of the.