From Lowbrow Customs: Mount your solo seat easily with these weld-on solo seat spring mounts. Made of 1018 cold rolled steel for easy welding, they are 1" diameter with a threaded 3/8"-16 shaft for the spring to sit over. They are coped at 1" to fit standard size frame tubing, but can easily be enlarged to fit larger 1 1/4" tube if necessary. Included are a heavy-duty chrome steel washer and a chrome nylock nut for each mount to secure your seat springs to your frame. Price is for a set of two mounts, two washers and two nuts. Made in Ohio, USA.
These are for mounting coil springs only, for hairpin style springs you want to use the Solo Seat Hairpin Spring Mounting Kit