These are Splined Wheel Nuts from Traxxas.

This is a Stock part for:

1/10 Stampede 2wd VXL (3607)
1/10 E-Maxx Mamba (3908)
1/10 T-Maxx 2.5 (4910)
1/10 Revo 3.3 (5308)
1/10 Revo 3.3 (5309)
1/10 Summit (5607)
1/10 E-Revo Mamba (5608)
1/10 Ford F-150 SVT Raptor 2wd (5806)

This is an Optional part for:

1/10 Monster Jam Trucks (3602)
1/10 Stampede 2wd XL-5 (3605)
1/10 Rustler XL-5 (3705)
1/10 Rustler VXL (3707)
1/10 E-Maxx EVX2 (3903)
1/10 T-Maxx 3.3 (4907)
1/10 T-Maxx 3.3 (4908)
1/10 T-Maxx 3.3 (4909)
1/10 E-Revo EVX2 (5603)
1/10 E-Revo EVX2 (5605)
1/10 Slash 2wd XL-5 (5802)
1/10 Slash 2wd XL-5 (5803)
1/10 Slash 2wd XL-5 (5805)
1/10 Slash 2wd VXL (5807)
1/10 Slayer Pro 4x4 (5907)
1/10 Stampede 4x4 VXL (6708)
1/10 Slash 4x4 Platinum (6804)
1/10 Slash 4x4 Ultimate (6807)
1/10 Slash 4x4 VXL (6808)
 

Features:

• Aluminum construction
• Blue anodized in color
• Splined
• 17mm

Includes: 

Four (4) Wheel Nuts