https://www.amazon.com/gp/product/B08P1WQSNP/ref=ppx_yo_dt_b_asin_title_o00_s01?ie=UTF8&th=1 Head Diameter: 8.5mm

https://www.amazon.com/gp/product/B08GY6MT68/ref=ppx_yo_dt_b_asin_title_o00_s01?ie=UTF8&th=1 Head Diameter 9.3mm max

https://www.amazon.com/gp/product/B07S8SJ97R/ref=ppx_yo_dt_b_asin_title_o00_s01?ie=UTF8&th=1 Nut diameter 10mm

https://www.amazon.com/Floyutin-Stainless-Flange-Thread-Fastener/dp/B0BXKDKR4Q/ref=sr_1_8?crid=2Y7M0Z4N4YBF3&keywords=m4%2Bnut&qid=1703026476&s=industrial&sprefix=m4%2Bnut%2Cindustrial%2C79&sr=1-8&th=1 Net diameter 9.8mm

https://www.amazon.com/Uxcell-a15071400ux0041-M4x8mmx0-5-Stainless-Washer/dp/B015A39OOO/ref=sr_1_6?crid=3QIUTNZC8YGEZ&keywords=m4+washer&qid=1703026569&s=industrial&sprefix=m4+washer%2Cindustrial%2C68&sr=1-6 Washer diameter 8.0mm

https://www.amazon.com/dp/B0CCT6Z276/ref=sspa_dk_detail_1?pd_rd_i=B0CCT6Z276&pd_rd_w=F8U9F&content-id=amzn1.sym.f734d1a2-0bf9-4a26-ad34-2e1b969a5a75&pf_rd_p=f734d1a2-0bf9-4a26-ad34-2e1b969a5a75&pf_rd_r=1FF4HCTXVNFAB3AC6B0F&pd_rd_wg=PrFIE&pd_rd_r=350e262b-7ef4-40ab-ad27-5262ebaa7674&s=industrial&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWw&th=1 Washer diameter 6.4mm