professional to control the amount of tension applied to the first or second ends 42 a 44 a of the tether as necessary for example when the delivery system is being advanced through the vasculature of the patient the thumbwheel may allow the medical professional to maintain the desired amount of tension on the first end 42 a of the tether to maintain the proximal attachment member 32 securely coupled to the distal end 26 of the delivery tube 20 once the embolic coil 30 is properly positioned within the patient the medical professional can use the thumbwheel to release the tension on the first end 42 a of the tether and apply tension on the second end 44 a until the knot 46 releases from the eyelet again the immediate release affected by this knot configuration allows the embolic coil to be 100 detachable since no portion of the tether remains in contact with the proximal attachment member 32 once the knot is untied the releasable knot 46 is therefore superior to simple loop designs that require the free end of the tether to be pulled all the way through the embolic coil attachment mechanism as discussed above the process of removing the tether tends to cause displacement kickback of the deployed embolic coil into the parent vasculature referring to fig6 once the embolic coil is released from the distal end 26 of the delivery tube 20 the delivery tube is retracted into the lumen 12 of the microcatheter 10 the entire.