(Warning: this posting will immediately descend to crude jokiness on male genitals and masturbation, so it’s not to everyone’s taste)
To celebrate Masturbation Day, today’s notable occasion (in my household, every day is jack-off day, but the celebratory holiday comes around only once a year): the Zwicky Linemaster hose end pressure controller, from a vintage UK ad for aviation supplies (advertised on eBay), with its language repurposed here to cover the fluid pressure of ejaculation (which varies considerably in the male population, while being largely out of conscious control):
(#1) The ad from eBay, for some Zwicky Limited (of Buckinghamshire in southeast England) aircraft equipment, for controlling hose pressure during fueling