FLX3_04 is a dual mount, 3mm, flexible round light pipe with a length of 4.0 inches and made of optical fiber. Fit into a hole on 0.171” (4.34mm). Fit’s SMB 200, SML 190 and SMQ 250 Series (sold separately). Panel thickness for SML190 lens: 1/32” (0.79mm) to 1/16” (1.60mm) and for SML 200 and SMQ 250 lens: 1/16” (1.60mm) to 1/8” (3.48mm). For added security for SMD 200 lens and SMQ 250 lens use SPC 040 spacer (sold separately) For best result use only narrow viewing angle non-diffused LEDs with output power greater than 100mcd. Fit’s the following LED mounts: SMD22, THR22 and THR522 (sold separately).