120 sleeve 130 supports the outer and inner support members 120 and 122 sleeve 130 is detachably connected to ring 132 by means of a shear wire or other shear mechanism 134 ring 132 is seated on shear member 136 which abuts the lower housing 108 in operation the plug 102 will resist downward compression through flow bore 109 as the glass or ceramic structure of plug 102 will be predominantly stressed by relatively uniform compressive forces since the edges of the plug 102 are firmly supported between the piston 114 above and the inner and outer support members 120 and 122 below if it is desired to destroy plug 102 a pressure must be applied into flow bore 109 which exceeds the shear value of the shear wire 134 for this reason the value of the shear wire or other shear mechanism must be set in excess of those operating pressures under which plug 102 is designed to resist increased pressure downward through flow bore 109 will act across the surfaces of plug 102 and piston 114 urging them downwardly along with outer and inner support members 120 and 122 and sleeve 130 when shear wire 134 is sheared inner sleeve 130 will move downward with respect to ring 132 and shear member 136 as this occurs ring 132 blocks downward movement of outer support member 120 but not inner support member 122 the radial support of the edges of plug 102 at shoulders 126 will now be removed and plug 102 will be supported solely by the protuberances 128 of the outer support member 120 this creates non uniform shear forces proximate the edges of the plug 102.