Slightly behind the times...Been doing them for 5 years. I use a 29 gauge 1/2 inch needle in shoulder by injecting on a 45 degree angle not straight in. Straight in would may be more IM. I suggest this technique when parents who have children autism are using b-12 from their Dr. It tends to have less side effects by mimicing a slow release vs an immediately release. Giving an autistic child a IM shot of methyl b-12 with the wrong genetic snps will cause elevate stimming where as giving it underneath the skin there is less to likely to occur.