He got them from element14. Note you need two pieces. Read the post for more details.
GEL MEC - GVD-1010-40
DAMPER, 10MM GEL MECGVD-1010-40
Manufacturer: GEL MEC
Order Code: 1422144
GEL MEC - SCR10UNC
FIXING BOLT, UNC6-32, FOR GVD-10 GEL MECSCR10UNC
Manufacturer: GEL MEC
Order Code: 1422159