Cavitron FSI Focused Spray 25K FSI-10 insert light blue. FSI-10, 25 kHz. Provides increased scaling and deplaquing. Focuses water where it is needed. Indicated for gross deposit removal. Cavitron Focus Spray ultrasonic inserts are used with all Cavitron ultrasonic scaling units for maximized scaling and deplaquing performance with less water. It features a patented internal water delivery system that directs water to the insert tip, releasing water where it is needed most.These inserts facilitate the removal of gross deposits for an enhanced view of working area.