shown in phantom configurations ring portion 51 having top surface 52 and bottom surface 53 and arced ring walls 54 is fixedly attached to strainer portion 11 strainer portion 11 is removably received within drain opening 31 which has an adjacent drain rim substrate 32 continuing with fig3 a 3 b and 3 c the disposable drain strainer 100 105 120 ring portion 51 and arced ring walls 54 further comprise a sealing rim 55 that engages with and forms a seal with adjacent drain rim area 32 of drain opening 31 this seal between sealing rim 55 of ring portion 51 and adjacent drain rim area 32 prevents the seepage and passage of wayward debris from bypassing strainer portion 11 and undesirably entering drain opening 31 and potentially clogging the drain piping optionally ring portion 51 further comprises a plurality of elongated channels see fig4 a and 4 b convex configuration 101 is engaged when ring portion 51 forms the seal with adjacent drain rim area 32 concave configuration 102 is engaged when top portion 52 of ring portion 51 is pressed for example by thumb or finger 103 as force is applied to top portion 52 by thumb 103 and.