A clip buckle assembly suitable for use in an animal collar has two releasably interlockable buckle members and an adjustment means having a tongue extending between a buckle member and a stop at the end of the tongue. The tongue is arranged to pass through a slider having a gripping means configurable between an open configuration, wherein the first tongue is free to slide through the first slider and a closed configuration, wherein the first tongue is held locked against the first slider when the first slider is urged in a slackening direction from the proximal towards the distal end of the first tongue, whereby the slider is arranged to be fixable against slackening at any of a plurality of positions along the first tongue. The stop is arranged to prevent the tongue from disengaging from the slider when the first slider is urged in the slackening direction. Also disclosed is a collar using the adjustable clip buckle assembly. The arrangement allows for rapid deployment of the collar by means of the clip buckle to fasten the collar and the tongue/slider arrangement for tightening or slackening without risk of the collar disengaging by the tongue pulling out of the slider.
