MAYER PIPE — Proxy Solicitation & Information Statement 2026

May 15, 2026

Notice of 2026 Annual General Meeting - Mayer Steel Pipe Corporation

I. The AGM of 2026 is scheduled to be convened at 9:00 a.m. on Thursday, June 18, 2026 at No. 83, Sec. 3, Civic Blvd., Zhongshan Dist., Taipei City (Miramar Garden Taipei). Shareholder registration for this meeting will begin at 8:30 a.m. at the same venue.

II. Main agenda:

(I) Report Items: 1. Report on the 2025 business status. 2. Audit Committee's review of the 2025 final accounts report. 3. Report on the distribution of employee remuneration and director remuneration for 2025. 4. Report on the distribution of cash dividends from 2025 earnings. 5. Report on the remuneration received by the Company's directors in 2025. 6. Other Report Items.

(II) Ratification Matters: 1. The Company's 2025 final account books and statements. 2. The Company's 2025 earnings distribution proposal.

(III) Extempore Motions.

III. The Company's 2025 earnings distribution proposal has been resolved by the Board of Directors as follows:

Cash dividend: NT$480,656,376, NT$1.8 per share.

IV. In accordance with Article 165 of the Company Act, share transfer registration will be suspended from April 20, 2026 to June 18, 2026.

V. If any matter in the reasons for convening this Annual General Meeting is subject to the requirement under Article 172 of the Company Act to explain the main content, please directly access the Market Observation Post System at

[https://mops.twse.com.tw/mops/#/web/home/SingleCompany/ElectronicDocumentDownload/AnnualReportsAndShareholdersMeetingRelatedInformation/AnnualReportsAndShareholdersMeetingRelatedInformation(IncludingDepositaryReceiptInformation)]. Shareholders are requested to enter the Company's stock code and year to inquire about the reference materials for each proposal of the Annual General Meeting, or the meeting handbook and supplementary meeting materials.

VI. The proxy tallying and verification institution for this AGM is the Shareholder Services Department of IBF Securities Co., Ltd.

VII. Except for announcements required by applicable laws and regulations, this notice is hereby duly served, together with one attendance sign-in card and one proxy form for the AGM enclosed. Shareholders are respectfully requested to review this notice and attend the meeting if convenient. If a shareholder attends in person, please complete the second copy of the

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attendance sign-in card, affix the registered seal or signature, and bring it to the venue for registration on the meeting date; there is no need to return it by mail. If a proxy is appointed to attend the meeting, please complete the second copy of the proxy form, affix the registered seal or signature, and deliver it to the Company's shareholder services agent, IBF Securities Co., Ltd.

Shareholder Services Department (Address: 15F, No. 188, Sec. 5, Nanjing E. Rd., Songshan Dist., Taipei City 105411; Tel: (02) 2528-8988), five days before the meeting date to facilitate issuance of the attendance sign-in card. If the attendance sign-in card is not received before the meeting, please bring identification documents directly to the venue to apply for reissuance.

VIII. If any shareholder solicits proxy forms, the Company will compile a summary statement of solicitor solicitation information and disclose it on the Securities and Futures Institute website on May 18, 2026. Investors may directly enter the website address https://free.sfi.org.tw and access the "Proxy Solicitation Free Inquiry System" to enter the search criteria for inquiry. (Stock Code: 2020)

IX. For this shareholders' meeting, shareholders may exercise voting rights electronically during the period from May 19, 2026 to June 15, 2026. Please directly log in to the Taiwan Depository & Clearing Corporation "Shareholder e-Service" webpage and vote in accordance with the relevant instructions (Website: https://stockservices.tdcc.com.tw).

X. Your attention and action in accordance herewith will be appreciated.

Sincerely,

Board of Directors of Mayer Steel Pipe Corporation