ASI has developed a new design of Adjustable Makeup-Flow Splitter, which is the 691 series. The 691 series splitters provide ASI customers with extended dynamic range, precise split setting and reduced dead volume. In particular, the Vernier scale feature enables the users to set splits reproducibly and to operate the adjustable knob smoothly. 

https://www.hplc-asi.com/adjustable-makeup-flow-splitters/