In New update we can add meta description up to 300 characters before update it was 155 characters) with spaces. its confirmed update and currently new deception with 300 characters visible on search window.its really nice update to describe your web page. for more you can learn. Moz , search engine land
SEO, SEM, Google Updates, SMO, PPC, and Digital Marketing Guide. On page techniques, Off page techniques Seo Basics, Seoguru.