SheepFarmer, I have a Lock n Lube, but it's too long for some spots, so I got this locking attachment
Lock on Grease Gun Coupler, Grease Gun End, Easy Connect/Disconnect Zerk Coupler https://www.amazon.com/dp/B00TLD6VR8/ref=cm_sw_r_em_apa_yblGzbEXGC6BR
It, too, only takes one hand to engage and...