ImportBvalvec[]

will prompt to select the *.bval and *.bvec files.

ImportBvalvec[file]

if file is either a *.bval or *.bvec it will automatically import the *.bval and *.bvec files.

ImportBvalvec[*.bvec,*.bval]

imports the given *.*.bvalbval and *.*.bvecbvec files.