Store › Springfield KingPin Unintentional Detach Retention Cup - Plastic [2100175] Springfield KingPin Unintentional Detach Retention Cup - Plastic [2100175] $4.99 KingPin™ Unintentional Detach Retention Cup - PlasticReplacement standard post pin for use in KingPin™ standard base. Add To Cart Added! KingPin™ Unintentional Detach Retention Cup - PlasticReplacement standard post pin for use in KingPin™ standard base.