Shaft Nut located on the top of the shaft (smaller Nut of the two), this nut tightens the Pneumatic Cylinder in place. 

Specifications:

• Stainless Steel
• Inside Diameter 3.40mm (0.13")
• Outside Diameter 6.90mm (0.27")

Compatible With:

• E-FP-50
• E-FP-100
• E-FP-250
• E-FP-500
• E-FP-1000
• E-FP-50-D
• E-FP-100-D
• E-FP-250-D
• E-FP-500-D
• E-FP-1000-D
• E-FP-1000-D2
• E-FP-100-DHH
• E-FP-500-DHH
• E-FP-1000-DHH

California Residents: read Proposition 65 warning.