Lip closure - being able to create and maintain a seal with your lips - is a fundamental oral motor skill for successful speech and feeding development. For feeding, it's how we do things such as drink from a straw, remove food off of a spoon, keep food in our mouths while we chew, keep saliva in the mouth at rest (which prevents drooling), etc. For speech, it's how we produce labial sounds (/p/b/m/) to say pop, mom, boy, etc., which are all articulated with the lips together. Being able to round the lips is important, too. Lip rounding is needed in order to blow bubbles, blow out candles, blow a kiss, and say certain speech sounds like "ohhh".
Puheterapiavalineet.com
ARK'S Every Lip Blok Suffolk Center for Speech
Button Pull Exercise Kit – Therapy Resources LLP
Button Pull Lip Closure Activity - ARK Products, LLC
Pro Button Set for Lip Strength by Ark
ARK's proButton™ Set for Lip Closure/Strength - Sensory Needs Ltd
Button Pull Exercise Kit – Therapy Resources LLP
ARK's proButton™ Set for Lip Closure/Strength - Sensory Needs Ltd
Ark Probutton - Speech therapy material