These canvases are advertised incorrectly and aren't 30cm high or wide, or even deep when extended. They're 25cm high and a paltry 19cm at the widest part. The lip to hold the canvas steady is about 2mm and virtually useless. Would possibly hold an A3 canvas at a push if you used blue tack. As a side point, the amount of stuff I've had to send back lately as it's not as advertised is becoming ridiculous, getting more like eBay.