This exciting cover celebrates an important milestone in the title's long run. 300 issues of any magazine or comic is an impressive achievement. The Legion of Super-Heroes made their first appearance in Adventure Comics #247. Over the next few years, they made several other appearances in this title. Superboy had been the sole cover subject of Adventure Comics since he moved over from More Fun Comics; that move took place in issue #103 of Adventure. With this issue, the Legion begins their very long run as a regular feature and they also start to share the cover with Superboy. The Legion would continue to appear on the cover until issue #380.This memorable cover highlights several of the Legionnaires. Featured are Triplicate Girl, Saturn Girl, Cosmic Boy, Sun Boy and Lighting Lad. The issue also finds Mon-El being freed from the Phantom Zone so he can join the Legion in the future. A highlight of the cover is an appearance of the Legion's Clubhouse in the center. The book has off-white to white pages. It is CGC-certified 8.5 (VF+). This copy is tied with three others as the second highest graded copy on the CGC Census.