Hi, there! Thank you for asking us with regards to our 3/4" coupling. Yes, it is adjustable. When collapsed, it measures 4 1/2"(L) x 1 1/2"(H) x 1 1/2"(W). Fully extended dimensions are 6 1/4"(L) x 1 1/2"(H) x 1 1/2"(W). Here's a specification sheet for additional details. Thank you and we hope to see you again here at PlumbersStock.com!