GR6 Grommet Connectors – best way to connect diffusers to header pipe. SSI AERATION GROMMET CONNECTIONS Simple to install on site, compact to ship and move Grommets are inserted into a 1-1/4”(32mm) straight hole drilled into PVC or Stainless pipe from 2.5” to 6” diameter (60mm to 150mm), Sch 40 or thinner wall Grommets can be solvent welded to PVC pipe. Affordably priced and time tested over 15 years worldwide SSI’s grommet is an economical and reliable product used to connect disc diffusers and coarse bubble diffusers like the SSI Relia-Ball to header pipe. Material: Soft PVC (standard) Installs on a 1-1/4” (32 mm) chamfered drilled hole. Installation of PVC grommet is recommended on plastic piping only.