Using the gri gri as an auto belay, The unit must be modefied for use as an auto belay, the method that I find most eficient is to drill a small hole in the plastic back of the unit,aproximately at the end of the word petzle and corosponding with the letter M in the word "made"in france on the aluminium body. and a corosponding hole on the inside of the unit ,again in the plastic, there is a small triangle formed in the plastic very close to the steel axle that the cover spins on (the main axle) cut a triangular hole in this plastic ,this allows a string to be fed in from the outside (near the end of the word petzle on the plastic back) to the inside (the triangular hole cut near the main steel axle) then tie a water knot or overhand knot to prevent the string from bieng pulled out of the hole.now the hard part is to stuff the knot into the triangular hole so the cover will shut on the unit, I find the diameter of string is important so that this is possible, I use 3mm string kernmantle construction, similar to boot lace. when this is done, then tie of the other end of the string to form a loop ,with a figure 8 knot or again a water knot, to allow it to be cliped in to a caribiner.this is a usfull keeper for the unit to allow for no hands removal after it gets hot from long rappels,but more importantly it is now the attachment point for the chest harness ,this keeps the unit upright and functional (but is not the load bearing attachement!) the load bearing connector for this set up is a STEEL D shaped malion, as this will allow the load to be placed anywhere along the malions circomferance without a cross loading failure happening,as would be possible if an aluminium crab were used, it should be connected through the leg loops and the waist band ,as per tieing in of the rope.the next procedure is to cut away a part of the aluminium on the swinging cover flap of the unit, "this is not recomended by petzle" (there I've covered my ass) now the part you are looking for is the part that does a 90 degree turn and is in the shape of a long sided triangle,next to where it says "warning proper training is essential before use",it is important that you do a good job of fileing it smooth to allow the rope to move freely through the slot created, and not have any burs that might otherwise damage the rope.when this is done you are ready to go solo aiding the important (read life saving) aspects of use are that the upward pulling anchors be bombproof ,ie new stainless bolts, good trad gear, and some dynamic feature, like the pigs be a counter weight, or screamers (tear away slings desighned to provide a dynamic quality to shock loads) also a knot in the end of the rope to provide security agaisnt the rope weight puling the rope through the unit when the critical balance point is reached ,I find that tib locks or a prusic on the lead line just before the half way mark and every five to ten meters after that prevent the rope weight from pulling through the free end of the rope, some people also tie in back up knots in the lead line as a form of redundancy to the units functionality,ie back tieing. I have never had the unit not function so I dont bother with this but that is totally up to you , once at the top of a pitch then secure the line to your new anchor and rapell to clean the route ,the gri gri comes to the party as half of the jumar rig in conjunction with a prusic or jug once the bottom anchor has been cleaned. here are some photo's of my rig to give you a better understasnding of how to modernize the unit. all the best with your solo aiding (I also free climb in this manner,when I am short on belayers). MUKI WOODS.