An antique treen straw splitter with six different sizes of fins/ blades used foir cutting different thicknesses of straw splints. This is an interesting example as the blade cutters with seven divisions would give really fine straw. It also has the makers name Austin on it.
The straw would be pulled through one of these splitters dividing the straw into different thicknesses of splints depending on which size was required. This would then be used for straw plaiting.
James Austin was a, wood turner of Akeman Street, Tring, and is listed in the Post office directories for Hertfordshire in 1850, 1862 and 1870, The 1851 census lists him as a 45 year old turner, born in Tring and living in on the eastern side of Akeman Street, just up from the High Street, and close to where the Victoria Hallnow stands. 

This humble device transformed straw plaiting in the UK enabling finer straw of superior quality to be produced rivalling European countries.  
For more info
https://www.opusantiques.co.uk/single-post/2018/06/05/The-Humble-Antique-Treen-Straw-Splitter