Question A new space suit

Hola Sarah A.

This is a good question. Even though “un traje espacial” is masculine, in your sentence the adjective does not refer to the suit itself. Instead, it refers to “la calidad”, which is a feminine noun. For that reason, the correct form is “su calidad es muy buena”.

If the adjective were describing the suit directly, then it would indeed take the masculine form: “el traje espacial es muy bueno.” The key is to identify which noun the adjective is modifying.

I hope this clarifies it. Let me know if you have any further questions.

Saludos

Silvia