Open Helm

An Open Helm is the first Helm-class headwear available throughout the Golden Sun series. It is sold in armor vendors at Bilibin and Imil in Golden Sun, at Alhafra and Garoh in Golden Sun: The Lost Age, and at Harapa in Golden Sun: Dark Dawn. This helm can be equipped on all warrior-style Adepts in both games, namely Isaac and Garet in the first game, together with Felix and Piers in the second, followed by Matthew, Tyrell, and Eoleo in the third. It increases the equipped Adept's base Defense rating by 9 points. Its buy value is 180 coins and its sell value is 135 coins.

In Golden Sun when the Open Helm can be first bought in Bilibin, it is a pretty good upgrade to the Leather Caps that Isaac and Garet are probably wearing, and is worth your generally low amounts of funds you would most likely have at that point. They're much better worth your money than the Wooden Cap, which has a single negligible extra defense point over the Open Helm but costs over twice as much (400), so it would only make sense from a financial perspective to only buy open helms for Isaac and Garet.

In The Lost Age, an Open Helm might be an okay buy for Felix once the party reaches Alhafra, but be advised that in the town Mikasalla which can be entered even before Alhafra, the far stronger Bronze Helm is sold for 600 coins, so it is very likely a much better idea to shop there.