Spire.Office for .NET is a combination of Enterprise-Level Office .NET components offered by E-iceblue.
It includes Spire.Doc, Spire.XLS, Spire.Spreadsheet, Spire.Presentation, Spire.PDF, Spire.DataExport, Spire.OfficeViewer, Spire.PDFViewer, Spire.DocViewer and Spire.Barcode....

Spire.Office contains the most up-to-date versions of the above .NET components.

In this releases of NET4.0:

Spire.Barcode.dll v4.1.1
Spire.Common.dll v10.3.8
Spire.DataExport.dll v4.1.9
Spire.Doc.dll v8.3.15
Spire.DocViewer.Forms.dll v5.1.1
Spire.Email.dll 3.3.0
Spire.License.dll v1.3.8
Spire.OfficeViewer.Forms.dll v5.3.7
Spire.Pdf.dll v6.3.11
Spire.PdfViewer.Forms.dll v5.1.4
Spire.Presentation.dll v5.3.6
Spire.Spreadsheet.dll v4.3.1
Spire.XLS.dll v10.3.8

Only for V.I.P