This is a 4" full open vacuum port dust boot system made out of 1/2" clear Plexiglass with an extended reach specifically designed for spind;e/routers with extended collets or for those extra long end mills. The boot features a split removable magnetic base that holds a transparent flexible screen that allows viewing of the cutting tool in progress. Magnetic base is easily removed that allows for full access to tool install. Design to fit the spindle/router size selected and will accept a 4" standard flex hose. Distance from bottom of top plate to sceen tips is 100mm. NOTE: If your spindle/router size is not listed you may order (CUSTOM spindle/router dia) and send message with the spindle/router size requirement. Price listed covers any size up to 90mm. For size larger than 90mm sent message for a quote. For 2.5" vacuum port see item # B0D2JGSBGC