Channel Integration is a crucial task for retailers in order to generate a seamless customer experience. This is particularly the case for assortments. Customers expect an identical assortment along all channels or customer confusion can occur, potentially leading to purchase abandonment or postponement and thus to losses in sales. Mental models can help to simplify complex systems and behaviour and can support managers in decision-making processes. This paper builds on a mental model approach to visualize the dynamics and trade-offs of the three critical objectives in omnichannel assortment management: assortment integration, customer confusion reduction, and purchase postponement/abandonment reduction, to assist retailers in decision-making through the depiction of different scenarios and objective achievements. Recommendations for actions are provided for each scenario eventually helping retail managers in improving understanding and decision-making for omnichannel assortment decisions.