Hello Mark! Thank you for your inquiry. The 10" 3 Tooth Blade is compatible with the ECHO Straight Shaft Trimmers only. This is not a universal blade.
Yes, this will work on a GT-225.
yes all blades need a conversion kit
No, this will not work on a Dewalt 20v trimmer.
No, the curved shaft models do not accept metal blades.
Hi Mando, Thanks for visiting our site! This blade will fit onto Echo SRM trimmers that are straight shaft trimmers. It will not fit onto curved shaft trimmers. A blade arbor kit is required for use with any SRM Echo trimmer. Here is an example of a blade kit that you can use: https://www.homedepot.com/p/ECHO-8-in-8-Tooth-Brush-Blade-Conversion-Kit-20-mm-99944200422/100675438 Thank you for asking, -Travis
No, the SRM-225 is not compatible with 25 mm arbor blades. Any ECHO metal blades that have a 20 mm arbor can be used with the SRM-225.
To further assist you with your inquiry, please contact ECHO's Consumer Support Department at 1-800-432-ECHO (3246). Our Representatives are available Monday - Friday between 8:00 a.m. - 4:30 p.m. Central Standard Time.