This Moleskine is the perfect size for a purse or pocket, but has a heavy duty cover, so it won't get torn and beat up and the elastic band will keep it closed so your drawings don't get marred and bent.  The pages are thick and sturdy, perfect for taking a variety of mediums, and for preventing show-through from the otherside.  I love carrying this with me to do  simple little pen and ink sketches.