Used JPfm SplitFS for Windows?
Developer’s Description
By Neembuu
JPfm is a java language binding for pismo file mount. SplitFS is made using JPfm. SplitFS can merge hundreds of *.001 type of splits as big as 100TB in size in about 5 seconds. This is possible because it doesn't actually merge the file, it creates a virtual folder and creates a virtual "merge" file inside it.
Explore More

MKVcleaver (64-bit)
Free
MKVcleaver Portable (32-bit)
Free
SysInfoTools PDF Split and Merge
Trial version
PDF Explorer
Trial version
DNC Precision Free Edition
Free
FileShred
Free
AltDataRecovery
Trial versionTDP x-Ray
Trial version
Repair My Excel
Paid
EF Multi File Renamer Portable
Trial version
MeinPlatz
Free
Fast Duplicate File Finder
Free