Uni-Ball Signo RT1 UMN155-038 Gel Ink Pen 0.38mm Red Box of 10 - image 1
Uni-Ball Signo RT1 UMN155-038 Gel Ink Pen 0.38mm Red Box of 10 - image 2
Uni-Ball Signo RT1 UMN155-038 Gel Ink Pen 0.38mm Red Box of 10 - image 3
Uni-Ball Signo RT1 UMN155-038 Gel Ink Pen 0.38mm Red Box of 10 - image 4
Uni-Ball Signo RT1 UMN155-038 Gel Ink Pen 0.38mm Red Box of 10 - image 5
Uni-Ball Signo RT1 UMN155-038 Gel Ink Pen 0.38mm Red Box of 10 - image 6
Uni-Ball Signo RT1 UMN155-038 Gel Ink Pen 0.38mm Red Box of 10 - image 1
Uni-Ball Signo RT1 UMN155-038 Gel Ink Pen 0.38mm Red Box of 10 - image 2
Uni-Ball Signo RT1 UMN155-038 Gel Ink Pen 0.38mm Red Box of 10 - image 3
Uni-Ball Signo RT1 UMN155-038 Gel Ink Pen 0.38mm Red Box of 10 - image 4
Uni-Ball Signo RT1 UMN155-038 Gel Ink Pen 0.38mm Red Box of 10 - image 5
Uni-Ball Signo RT1 UMN155-038 Gel Ink Pen 0.38mm Red Box of 10 - image 6
Uni-Ball Signo RT1 UMN155-038 Gel Ink Pen 0.38mm Red Box of 10 - image 1
Uni-Ball Signo RT1 UMN155-038 Gel Ink Pen 0.38mm Red Box of 10 - image 2
Uni-Ball Signo RT1 UMN155-038 Gel Ink Pen 0.38mm Red Box of 10 - image 3
Uni-Ball Signo RT1 UMN155-038 Gel Ink Pen 0.38mm Red Box of 10 - image 4
Uni-Ball Signo RT1 UMN155-038 Gel Ink Pen 0.38mm Red Box of 10 - image 5
Uni-Ball Signo RT1 UMN155-038 Gel Ink Pen 0.38mm Red Box of 10 - image 6
Uniball

Uni-ball Signo RT1 UMN155-038 Retractable Gel Ink Rollerball Pen 0.38mm Red Box of 10

$22.53
$22.53
RRP $23.87
Or 4 payments of $5.63 with
Add items to a quote for bulk pricing, approvals, or purchase orders.

SKU: UMUMN155-038R

UPC: 4548351041878

MPN: UMN155-038R

Fine Red for Annotating Dense Print

Red at 0.38mm is a correction pen for crowded pages, built on the uni-ball Signo RT1, a retractable gel ink pen whose line widths uni-ball publishes in its 2026 catalogue.

Marking a closely typed page with a wide pen makes the correction harder to read than the original. A 0.38mm line, the narrowest of the three widths the catalogue lists for this model, goes between lines of type and into a narrow margin while staying clearly red. That is the useful combination for proofing, checking figures and annotating anything already full of text.

uni-ball publishes the pen as retractable, which suits a pen picked up and put down through a marking session, and publishes the ink as gel ink. The code on uni-ball's own site is UMN155-038, under the group code UMN-155, with the catalogue writing the same pen as UMN-155-38.

The 0.5mm red and the rest of the colours are at gel pens. More uni-ball is at uni-ball, other pens at pens, and the wider range at writing supplies.

Often ordered together

  • Retractable, as published by uni-ball for the Signo RT1
  • Gel ink, described on uni-ball's own page as new improved gel ink
  • 0.38mm line width, published in uni-ball's 2026 product catalogue rather than on the product page
  • Red ink at 0.38mm, fine enough to correct between lines of type
  • uni-ball publishes the model under the group code UMN-155, this width as UMN155-038
  • Supplied as a box of 10, all one colour
  • uni-ball describes the RT1 as an ultra fine pen for precision writing
  • Proofing and correcting closely typed pages
  • Margin notes on dense printed documents
  • Checking figures on spreadsheets and reports
  • Detailed marking of student work
  • Quality and inspection sheets with small fields

Shipping

Shipping is kept simple with flat rates for selected areas and free shipping where applicable. Large, bulky, rural or out-of-area orders may require additional freight, and our team will contact you if this applies. For a more specific estimate, simply add this product to a quote or visit our shipping page.

Delivery Times

Melbourne, Sydney, Brisbane, Adelaide — 1 to 3 business days
Perth — 1 to 5 business days
Regional & Outer Areas — 3 to 7 business days

Returns

If you have questions about returns, please contact us or visit our returns page for full details.

Specifications

Brand: uni-ball

Range: Signo RT1

Model Group: UMN-155

Manufacturer Code: UMN155-038

Mega Code: UMUMN155-038R

Colour: Red

Line Width: 0.38mm (published in uni-ball's 2026 product catalogue, not on the product page)

Ink Type: Gel ink

Mechanism: Retractable

Pack: Box of 10

Barcode: 4548351041878

Refill Code: Not published by the manufacturer

Country Of Origin: Not published by the manufacturer

Primary Distribution Centre

Factory 5, 12 Greenway Drive
Tweed Heads South NSW 2486

ABN 18 634 002 609

Get directionsContact us

FAQs

uni-ball's product page for the Signo RT1 does not publish a tip size. The 0.38mm figure is published in uni-ball's 2026 product catalogue, which lists the model in three widths. We have attributed it to the catalogue rather than the page so you can see which source it rests on.
uni-ball publishes no refill code for the Signo RT1, so we are not going to name one. Other Signo models take their own specific refills and guessing across models is how the wrong cartridge gets ordered. Ask us and we will chase the code through the supplier.
Correcting and annotating where there is very little room. Between lines of type, inside a narrow margin, or over a printed table. For broader marking and ticking, the 0.5mm red version of the same pen is the easier one to use.
Retractable. uni-ball states that on its own product page for this model, which is why we are comfortable publishing it. There is no cap.
Because uni-ball writes it two ways. The uni-ball website publishes this width as UMN155-038, and uni-ball's own 2026 catalogue writes the very same pen as UMN-155-38. We have used the website spelling throughout and flagged the difference rather than picking one silently.
Ten, all red. That is the pack we hold against UMUMN155-038R, read from this product's own record rather than assumed from the range.

Shipping & Delivery

Delivery time depends on your location, the size of your order, and the shipping option selected at checkout. For in-stock items, standard metro delivery in QLD, NSW and VIC is usually 1 to 7 business days. South Australia, Tasmania, Western Australia and the Northern Territory are generally 3 to 12 business days. Express delivery for eligible parcels under 3kg is usually 1 to 4 business days in QLD, NSW, ACT and VIC. Delivery estimates apply to in-stock items only and may vary due to carrier conditions or delays.

If you need to make a change to your order, please contact our team as soon as possible. Once an order has been processed or dispatched, changes may no longer be possible. You can contact us through our Contact Us page for assistance.

Mega Office Supplies ships orders Australia wide and occasionally internationally. The best avenue would be to contact us so we can customise a specific quote for you. Please note that associated international duties, taxes and levies will be the responsibility of the customer.

Returns, Refunds & Replacements

Mega Office Supplies accepts change-of-mind returns for unopened and unused products within 14 days from the invoice date, provided the item is returned in its original packaging and in resalable condition. Original shipping costs are not refundable, return shipping is the customer’s responsibility, and a restocking fee may apply depending on the product type and supplier. Some items, including electronics, assembled or installed furniture, food, beverages, medicines, custom-made products, and certain bulk or special-order items, are not eligible for return unless required under Australian Consumer Law.

If your order arrives faulty, damaged, or incorrect, please contact Mega Office Supplies as soon as possible. Where required under Australian Consumer Law, a repair, replacement, or refund will be offered. In these cases, Mega Office Supplies will cover reasonable return shipping costs, and photographic evidence may be requested to help process the claim. Items should be reported within a reasonable timeframe after delivery.