These Made in the USA bushings are the equivalent of the regular Sierra (20A) bushings. They use a standard "A" mandrel and work with the following kits: - Sierra Twist Ballpoint Pen Kit - Sierra Button Click Pen Kit - Sierra Button Click Pencil Kit - All Elegant Sierras - All Elegant Beauty Sierras - Sierra Grip - Sierra Nomad - Pensar Ballpoint Pen Kit - Virage Ballpoint Pen Kit