Adaptor, 1/4" TRS-Female to 3.5 mm TRS-Male, popular plug your big stereo headphone phono plug into the mini-stereo jack - big-to-small headphn conversion OR mini-stereo jack-out converted into the large 1/4" stereo-phono-out - 1/4" stereo F to 3.5mm stereo M - TRS=Tip + Ring + Sleeve - large studio monitor type headphones into a small portable device
🛒 More audio essentials for all your music making and sharing needs! Goto hotlinks below; works well in Chrome, Firefox, Safari... browsers:
♫   Hosa's versatile 100-240VAC travel-ready Universal Power Adapter
♫   Hosa 1/4" Stereo Female-3.5mm Male: plug your big studio headphones into the small jack / devices
♫   Hosa 3.5mm Stereo Male-2X 1/4" Female: adapt portable devices into mix-boards, combo amps, etc.
♫   Hosa's standard cable for plugging your personal device into car stereo
♫   XLR-XLR(F) Gender Bender: Converts Male XLR into Female XLR
♫   XLR-XLR(M) Gender Bender: Converts Female XLR into Male XLR
♫   Hosa 3.5mm (M) to 2X RCA L/R (F): Nifty adaptor for personal devices-into-home stereo systems, etc.
♫   Hosa 1/4" Cable Coupler: connect two shorter instrument or speaker cables to make a longer one!
♫   Hosa 1FT Piggyback Pigtail Daisy-chain power cord/pwr-outlet adder
♫   Hosa HEAVY DUTY Power Cord, Standard for Amps and Musical Instruments & Devices
♫   BREAKOUT that stereo headphone jack into dual RCA L+R allows quick hook-up of your keyboard/drum machine/etc to home stereo amp!
♫   3.5mm-3.5mm stereo cable: Plug your personal device into that car stereo / non-Bluetooth sound system w/mini 3.5mm stereo input!
♫   Impedance (Z) transformer; maintains higher signal quality when connecting that low-Z mic and high-Z equipment (i.e. mic-to-non-XLR combo amp)

Shipping & Handling Note: The shipping & handling rates may be significantly impacted by current energy/material/transport and/or holiday service/situation-costs. The default shipping & handling option here is USPS First Class/Ground delivered in a 4"x4"x4" to a 7"x5"x3" or similar small-medium standard box/Postal-Approved Protective Shipping Bag to accommodate this type of single-item/package, unless customer or supply demands otherwise. Faster delivery option(s) available, including Domestic Priority 2-3 Day service, however, First Class USPS is often delivered in 3 days, and typically 4 days to more-rural domestic regions.