Mont. Code Ann. § 27-18-1502

Before issuing the writ, the justice shall require a written undertaking in due form on the part of the plaintiff, except a local government, with two or more sureties, in a sum of not less than $50 or more than $300, to the effect that if the defendant recovers judgment, the plaintiff will pay all costs that may be awarded to the defendant and all damages that the defendant may sustain by reason of the attachment, not exceeding the sum specified in the undertaking.