Custom Hawley RetainerImpression Kit Size Guide Custom Hawley retainer is a removable appliance meant to maintain. This appliance is not used for closing gaps or realigning teeth. They have an acrylic base plate with thin wire clasps for retention. Custom Designed: Custom lab made from your impressions. Design may not be exact as listing photos and will vary by individual. If you want a specific design, please contact us after placing your order. Impression Kit Included: