From Melvor Idle
This page is up to date (v1.2.2).
Pet ID: melvorF:Gunter
Source: Runecrafting
Drop Chance: See: Acquiring Pets
Effect: +10% Chance to Preserve Resources in Runecrafting
Part of 100% Completion: Yes

Gunter is a pet acquired through Runecrafting. The chance to preserve resources from Gunter is additive with other resource preservation bonuses, such as those from Runecrafting Mastery, Agility obstacles, Crown of Rhaelyx, Runecrafting Skillcape, Max Skillcape, and Cape of Completion.

There is no best item to runecraft to acquire Gunter, all items are equivalent.