diff --git a/Optimization.md b/Optimization.md
index 7ab2115..737b4a8 100644
--- a/Optimization.md
+++ b/Optimization.md
@@ -87,16 +87,6 @@ The assigned file cookie can also be customized.
 
 Customizing the needle id and/or file cookie is an acceptable behavior. "strict monotonously increasing" is not necessary, but keeping file id in a "mostly" increasing order is expected in order to keep the in memory data structure efficient.
 
-## Customize Needle Id to 128 bit
-
-By default, the needle id is a 64-bit number. But sometimes a 128-bit UUID is desired as a needle id. Now it is also possible to use a 128-bit number as the needle id. But you would need to build the binary with a special tag "128BitNeedleId".
-
-```bash
-go install -tags 128BitNeedleId
-```
-
-Running this mode, the needle id generated from the master is still 64 bit. You are expected to replace the needle id with a hex encoded UUID without all the dash signs, "-".
-
 ## Upload large files
 
 If files are large and network is slow, the server will take time to read the file. Please increase the "-readTimeout=3" limit setting for volume server. It cut off the connection if uploading takes a longer time than the limit.