Parker 21SFAN13SXN SERIES 21 SF 1/4" Steel Nickel Plated Plug, Male NPT

Rectus 21 Series Couplers (pneumatic, air) up to 300 psi connect with Industrial Interchange Nipples except for the 1/8" size that connects only with the 1/8" European Profile Nipples. 
Parker's Rectus 21 Series Couplers are push to connect, single shut-off couplers that mate with nipples conforming to A-A-59439 (MIL-C-4109F, ISO 6150-B) standards. These couplers have a slim profile and are corrosion resistant with stainless steel locking balls and valve springs. The sleeve guard protects against accidental disconnection. The heavy duty version has a steel sleeve and a valve body. Couplers are available in a range of sizes and materials suitable for pressure up to 300 psi.
Rectus 21 Series Nipples (pneumatic) connect with 1/8" Rectus 21 Series Couplers. These are small-sized, single shut-off pneumatic couplings. 
Markets:

• Industrial
• Construction
• Automotive service and repair
• Factory automation

Features:

• Corrosion resistant valve with stainless steel locking balls and valve spring
• Heavy duty version has steel body and sleeve for durability
• Easy push to connect operation
• Slim profile is compact in confined spaces
• Sleeve guard protects against accidental disconnection
• Sizes 1/4" through 3/8" connect with nipples conforming to A-A-59439 (MIL-C-4109F, ISO 6150-B) standards for global interchangeability. :
• Unvalved nipple mates with valved coupler for a single shut-off connection

Applications: 

• Air compressors
• Pneumatic air tools and hoses
• Water lines
• Grease guns
• Cleaning equipment
• Paint applicators
• Drop-down air lines
• Blow guns
• Packaging equipment
• Automation equipment