How embarrassing. blush Been there, done that. Are you needing one for the new HD servos? The old EZ Servs used screws that fit Futaba Servos. This may or may not help:

Futaba servo Horn Screw Types & Sizes:

. Futaba Micro Mini servo - Nylon Output Shaft = Small Tapped Screws
Diameter: 1.80mm (0.07") Length: 4.20 mm (0.16")

. Futaba S33 and S133 Servos - Nylon Output Shaft = Tapped Screws
Diameter: 2.60mm (0.10") Length: 5mm (0.19")

. Futaba Small MG Horn Screws - Small Machined Screws.
Diameter: 2.00mm (0.08") Length: 4.4 (0.16") Washer Diameter: 4.4mm (0.17")

. Futaba servo Horn Screws - Nylon Output Shaft = Standard Tapped Screws: 
Diameter: 2.60mm (0.10") Length: 8mm (0.31")
S28 S128 S136 S9001
S29 S129 S138 S9102
S30 S130 S148 S9202
S31 S130G S3001 S9301
S32 S131 S3003 S9304
S34G S132 S5101 S9403
S35 S134G S9601
S48 S135
I personally tested the above screw in a Futaba S3010 and it fits perfectly. Seems to be a very popular size for nylon gear servos. Our product #NG2608 Rich

. Futaba servo Horn Screw - Metal Output Shaft = Standard Machined Screws.
Diameter: 2.60mm (0.10") Length: 5mm (0.19")
S3002 S9203 S9302
S3102 S9204 S9303
S3302 S9205 S9402 
S3801 S9206 S9404 S9405 

. Futaba Horn Screw - Nylon Output Shaft = Standard Tapped Screws
Diameter: 2.60.10mm (0.10") Length: 10.00mm (0.39")
S9401 S9102 S134 S136G
S9403 S9202 S9301 S3104 S9201

. Futaba servo Horn Screw - S125 Sail servo = Standard Machined Screw.
Diameter: 2.00mm (0.08") Length: 6.00 mm (0.23")

. Futaba servo S3150 Horn Screw 
Diameter: 3.00mm (0.12") Length: 6.00 mm (0.23")

. Futaba servo S9150 Horn Screw - Standard Machined Screw.
Diameter: 2.80mm (0.11") Length: 8.00 mm (0.31")

. Futaba servo Horn Screw Standard Machined Screw for S9152, 9155 & S9550
Diameter: 3.00mm (0.12") Length: 8mm (0.31")

Also found this about the HDD servos from a year ago. Again, may not help:

Futaba 3f (25 teeth) for driving spline/shaft
6.2mm spline (including teeth)

If I was a betting man I'd say this one:

. Futaba servo S3150 Horn Screw 
Diameter: 3.00mm (0.12") Length: 6.00 mm (0.23")

Thanks Dave these are the micro servos from the store with metal gears. No nylon.

Hi Will,

It's an M3 x 6mm long Machine Screw.

THANK YOU !

Holy Cats! Looks like I guessed right! Even a blind pig finds.............................. Well you know. LOL.

Good luck Will.