When rolling a critical success to craft any item you may pick one Roll Type from the following list. Then choose whether the created item will grant advantage or disadvantage when used for rolls of that type. These choices are usually based on the thoughts and feelings of the character at the time of crafting the item.
Adding an additional day to the crafting time of the increases the critical range of the crafting check by one.
An item can be intented with a minor effect which does not grant advantage or a magical effect, in this case the original crafting time of the item counts towards reducing the critical range of the check.
The most common minor effects are seeds of emotions, memories or sensations which are occasionally communicated to the bearer of the item.
Any skill you are proficient with, choose one
Any saving throw you are proficient with, choose one
Attack rolls against a foe or type of foe you have fought, choose one
All saving throws against a foe or type of foe you have fought, choose one
An item that grants advantage on rolls is Intented to that Roll Type for instance, Dexterity Save Intented Leather Boots.
And Item that grants disadvantage on rolls is Malintented on that Roll Type for instance Perception Check Malintented Bandanna