## 5 Discussion  
According to the interviewees, from the interviews conducted and the information collected, we have scrutinized a set of features that a warehouse seems to need to maximize 3 PLs' performance. By looking at the cross-case results, the only warehouse feature considered as mainly \"attractive\" (\"A\") by the respondents is the building, and this applies to most of the indicators. Specifically, in line with [32], the size and layout of warehouses are attractive for 3 PLs to optimize the building's productivity and utilisation. On the other hand, if a 3 PL wants to be flexible and be able to organize the internal spaces according to the specific customer needs, the warehouse should not have structural constraints (e.g., size of the building mesh), which limit the possibility of being adaptable [28]. The building should also be characterised by a regular layout and a height suitable for the activities carried out inside to potentially dedicate spaces for added value activities or increase the productivity of the warehouse itself. It emerges that when 3 PLs select or build a warehouse, they tend to look first at the features of the building, even before considering the location. This represents interesting evidence, which confirms the importance of maximizing efficiency and flexibility to improve the opportunity to make the best possible use of resources and maximize cost-efficiency. This goes along with the evidence emerging about the internal areas. Respondents see their role as enablers for providing added value services to the customers, considered a differentiating factor. Consequently, elements such as temperature-controlled environments and fire-fighting and safety systems are rated as \"O\" (i.e., good internal areas can proportionally improve the warehouse indicators). While this evidence seems to support the existing literature [28; 45], it is interesting to notice that internal areas are not rated \"attractive\". It would seem that the building's features come first, and how the internal areas are organized and equipped to differentiate the service provision later. Resource efficiency and flexibility requirements make a warehouse more attractive in the eyes of a 3 PL. \begin{table}
\begin{tabular}{l c c c c c c c c} \hline \hline \multicolumn{8}{c}{Warehouse Feature: Technical/Construction Specifications} \\ Warehouse Performance Indicators & Case 1 & Case 2 & Case 3 & Case 4 & Case 5 & Case 6 & Case 7 & Case 8 \\ Delivery lead time & O & I & M & I & I & O & R & A \\ On-time delivery & O & I & M & R & R & R & I & A \\ Flexibility & I & O & M & O & M & O & M & A \\ Responsiveness & I & M & M & O & I & R & M & A \\ Completeness of the logistics service & O & I & M & M & M & O & O & A \\ Labour productivity & A & R & M & O & A & O & A & A \\ Order processing cost & A & R & M & O & A & O & A \\ Warehouse utilisation & A & R & M & I & O & A & O & A \\ \multicolumn{8}{c}{Warehouse Feature: Internal Areas and Utilities} \\ Warehouse Performance Indicators & Case 1 & Case 2 & Case 3 & Case 4 & Case 5 & Case 6 & Case 7 & Case 8 \\ Delivery lead time & O & I & O & R & R & M & I \\ On-time delivery & O & I & O & M & R & R & M & I \\ Flexibility & I & M & O & R & R & R & O & M \\ Responsiveness & I & I & M & R & R & R & M & M \\ Completeness of the logistics service & O & O & M & R & M & M & O & O \\ Labour productivity & A & R & O & R & I & M & M & M \\ Order processing cost & A & R & A & R & I & O & O & M \\ Warehouse utilisation & A & O & M & R & R & A & O & O \\ Logistics building adaptability & O & I & M & I & I & A & O & O \\ \hline \hline \end{tabular}
\end{table} 
Table 5: _Cont._Location is considered an important aspect, frequently rated as \"O\" (i.e., a good quality location can improve the warehouse indicators proportionally) but not as \"attractive\". This is interesting evidence, which still suggests the importance of making strategic choices about the network configuration in terms of facility location decisions.