These punches are used to drill connection holes in PDMS layers.
 
Reusable Biopsy Punchers for PDMS hole drilling: 
Limited reusable, disposable drilling tools, with a sharp stainless steel cutting tip ideal cutting and drilling clean holes in PDMS layer.  The plunger is easy to use. These punches may be disposed of after use or cleaned and reused.
 
Seamless, extremely sharp stainless steel cutting edge and ease of use with plunger
Ribbed handle provides a secure grip and better control
Protective cap for each punch to maintain sharpness
Color-coded - Sizes marked on handle
Disposable sterile punch – Gamma Radiation - Single use
 
Punch Head Size Options:
3.0mm
1.5mm
1.0mm
0.5mm (without plunger)

Check the OD of the tubing you use to connect to your PDMS chip.