diff --git a/src/trodes_to_nwb/probe_metadata/128c-4s6mm6cm-15um-26um-sl.yml b/src/trodes_to_nwb/probe_metadata/128c-4s6mm6cm-15um-26um-sl.yml
index cfb640f..3187020 100644
--- a/src/trodes_to_nwb/probe_metadata/128c-4s6mm6cm-15um-26um-sl.yml
+++ b/src/trodes_to_nwb/probe_metadata/128c-4s6mm6cm-15um-26um-sl.yml
@@ -3,7 +3,7 @@ units: 'um'
 probe_description: '128 channel polyimide probe'
 num_shanks: 4
 contact_side_numbering: true
-contact_size: 20.0
+contact_size: 15.0
 shanks:
   - shank_id: 0
     electrodes: