We're working on the "O" sound right now and the middle-size tube has been so helpful for us. At first, our kid would not let us bring it near him, then he would hold it in his hand and now he will bring it to his mouth. A work in progress for sure but progress indeed!

excellent

They do a perfect job. And they are easy to clean.

My kid has been using the red and blue one for producing oo and oh sound and worked so far :)
I bought this from an intervention center and we have a OPT therapist right now but we are not using the yellow tube yet. For what sound is the yellow one?

The shapes and tubes are wonderful tactile cues for my tiny ones with Apraxia or Suspected Apraxia to elicit bilabials and /u/ vowel. My kids have learned to associate the sounds with the shapes and just the visual of the shape and tactile cue on the lips is enough to elicit the sound/or approximation!